421 lines
8.9 KiB
Text
421 lines
8.9 KiB
Text
{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Traits"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"1."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"// Fill in the two impl blocks to make the code work.\n",
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"// DON'T modify the code in `main`.\n",
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"trait Greetings {\n",
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" fn say_hi(&self) -> String {\n",
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" String::from(\"Hi\")\n",
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" }\n",
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"\n",
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" fn say_something(&self) -> String;\n",
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"}\n",
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"\n",
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"struct Student {}\n",
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"\n",
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"impl Greetings for Student {\n",
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"}\n",
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"\n",
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"struct Teacher {}\n",
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"\n",
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"impl Greetings for Teacher {\n",
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"}\n",
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"\n",
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"fn main() {\n",
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" let s = Student {};\n",
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" assert_eq!(s.say_hi(), \"Hi\");\n",
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" assert_eq!(s.say_something(), \"I'm a good student\");\n",
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"\n",
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" let t = Teacher {};\n",
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" assert_eq!(t.say_hi(), \"Hi, I'm your new teacher\");\n",
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" assert_eq!(t.say_something(), \"I'm not a bad teacher\");\n",
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"\n",
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" println!(\"Success!\");\n",
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"}\n",
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"\n",
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"main();"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"2."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"struct Fender {}\n",
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"struct Gibson {}\n",
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"\n",
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"trait Guitar {\n",
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" fn sound(&self) -> String;\n",
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"}\n",
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"\n",
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"impl Guitar for Fender {\n",
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" fn sound(&self) -> String {\n",
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" \"like Jimmy!\".to_string()\n",
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" }\n",
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"}\n",
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"\n",
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"impl Guitar for Gibson {\n",
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" fn sound(&self) -> String {\n",
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" \"like Slash!\".to_string()\n",
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" }\n",
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"}\n",
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"\n",
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"// Returns some struct that implements Guitar, but we don't know which one at compile time.\n",
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"// FIX the errors here, you can make a fake random, or you can use trait object.\n",
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"fn random_guitar(random_number: f64) -> impl Guitar {\n",
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" if random_number < 0.5 {\n",
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" Fender {}\n",
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" } else {\n",
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" Gibson {}\n",
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" }\n",
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"}\n",
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"\n",
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"fn main() {\n",
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" let random_number = 0.234;\n",
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" let guitar = random_guitar(random_number);\n",
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" println!(\"You've randomly chosen an guitar, and it sounds {}\", guitar.sound());\n",
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"}\n",
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"\n",
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"main();"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"3. Trait bound"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"struct Fender {}\n",
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"struct Gibson {}\n",
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"\n",
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"trait Guitar {\n",
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" fn sound(&self) -> String;\n",
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"}\n",
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"\n",
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"impl Guitar for Fender {\n",
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" fn sound(&self) -> String {\n",
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" \"like Jimmy!\".to_string()\n",
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" }\n",
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"}\n",
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"\n",
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"impl Guitar for Gibson {\n",
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" fn sound(&self) -> String {\n",
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" \"like Slash!\".to_string()\n",
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" }\n",
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"}\n",
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"\n",
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"\n",
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"// Implement `fn use_guitar` with trait bound in two ways.\n",
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"fn use_guitar<G>(g: &G) {\n",
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" println!(\"Sounds {}\", g.sound());\n",
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"}\n",
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"\n",
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"// Implement `fn sum` with trait bound in two ways.\n",
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"fn sum<T>(x: T, y: T) -> T {\n",
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" x + y\n",
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"}\n",
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"\n",
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"fn main() {\n",
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" let g = Fender{};\n",
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" use_guitar(&g);\n",
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" assert_eq!(sum(1, 2), 3);\n",
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"\n",
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" \n",
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" println!(\"Success!\");\n",
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"}\n",
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"\n",
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"main();"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"4."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"// FIX the errors.\n",
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"struct Pair<T> {\n",
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" x: T,\n",
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" y: T,\n",
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"}\n",
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"\n",
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"impl<T> Pair<T> {\n",
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" fn new(x: T, y: T) -> Self {\n",
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" Self {\n",
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" x,\n",
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" y,\n",
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" }\n",
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" }\n",
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"}\n",
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"\n",
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"impl<T: std::fmt::Debug + PartialOrd> Pair<T> {\n",
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" fn cmp_display(&self) {\n",
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" if self.x >= self.y {\n",
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" println!(\"The largest member is x = {:?}\", self.x);\n",
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" } else {\n",
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" println!(\"The largest member is y = {:?}\", self.y);\n",
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" }\n",
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" }\n",
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"}\n",
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"\n",
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"struct Unit(i32);\n",
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"\n",
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"fn main() {\n",
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" let pair = Pair{\n",
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" x: Unit(1),\n",
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" y: Unit(3)\n",
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" };\n",
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"\n",
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" pair.cmp_display();\n",
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"}\n",
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"\n",
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"main();"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"5. Array with trait objects"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"trait Guitar {\n",
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" fn sound(&self);\n",
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"}\n",
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"\n",
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"struct Stratocaster;\n",
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"\n",
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"impl Stratocaster {\n",
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" fn get_name(&self) {\n",
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" println!(\"Fender Stratocaster\");\n",
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" }\n",
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"}\n",
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"\n",
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"struct LesPaul;\n",
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"\n",
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"impl LesPaul {\n",
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" fn get_name(&self) {\n",
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" println!(\"Gibson Les Paul\");\n",
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" }\n",
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"}\n",
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"\n",
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"impl Guitar for Stratocaster {\n",
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" fn sound(&self) {\n",
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" println!(\"{}\", \"Sounds like Jimmy!\");\n",
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" }\n",
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"}\n",
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"\n",
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"impl Guitar for LesPaul {\n",
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" fn sound(&self) {\n",
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" println!(\"{}\", \"Sounds like Slash!\");\n",
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" }\n",
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"}\n",
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"\n",
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"fn main() {\n",
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" // // FILL in the blank to make the code work.\n",
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" let s = Stratocaster{};\n",
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" let lp1 = LesPaul{};\n",
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" let blacky = Stratocaster{};\n",
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"\n",
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" let guitars: [__; 3]= [__];\n",
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"\n",
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" // Iterate through the guitars and make them sound.\n",
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" todo!();\n",
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"}\n",
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"\n",
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"main();"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"6. &dyn & Box<dyn>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"// FILL in the blanks.\n",
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"trait Draw {\n",
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" fn draw(&self) -> String;\n",
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"}\n",
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"\n",
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"impl Draw for u8 {\n",
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" fn draw(&self) -> String {\n",
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" format!(\"u8: {}\", *self)\n",
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" }\n",
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"}\n",
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"\n",
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"impl Draw for f64 {\n",
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" fn draw(&self) -> String {\n",
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" format!(\"f64: {}\", *self)\n",
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" }\n",
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"}\n",
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"\n",
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"fn main() {\n",
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" let x = 1.1f64;\n",
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" let y = 8u8;\n",
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"\n",
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" // Draw x.\n",
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" draw_with_box(__);\n",
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"\n",
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" // Draw y.\n",
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" draw_with_ref(&y);\n",
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"\n",
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" println!(\"Success!\");\n",
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"}\n",
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"\n",
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"fn draw_with_box(x: Box<__>) {\n",
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" x.draw();\n",
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"}\n",
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"\n",
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"fn draw_with_ref(x: __) {\n",
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" x.draw();\n",
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"}\n",
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"\n",
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"main();"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"7. Static and Dynamic dispatch"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"vscode": {
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"languageId": "rust"
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}
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},
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"outputs": [],
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"source": [
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"\n",
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"trait Foo {\n",
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" fn method(&self) -> String;\n",
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"}\n",
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"\n",
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"impl Foo for u8 {\n",
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" fn method(&self) -> String { format!(\"u8: {}\", *self) }\n",
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"}\n",
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"\n",
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"impl Foo for String {\n",
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" fn method(&self) -> String { format!(\"string: {}\", *self) }\n",
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"}\n",
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"\n",
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"// IMPLEMENT below with generics. (static polymorphism)\n",
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"fn static_dispatch...\n",
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"\n",
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"// Implement below with trait objects. (dynamic polymorphism)\n",
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"fn dynamic_dispatch...\n",
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"\n",
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"fn main() {\n",
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" let x = 5u8;\n",
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" let y = \"Hello\".to_string();\n",
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"\n",
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" static_dispatch(x);\n",
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" dynamic_dispatch(&y);\n",
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"\n",
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" println!(\"Success!\");\n",
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"}\n",
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"\n",
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"main();"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Rust",
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"language": "rust",
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"name": "rust"
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},
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"language_info": {
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"codemirror_mode": "rust",
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"file_extension": ".rs",
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"mimetype": "text/rust",
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"name": "Rust",
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"pygment_lexer": "rust",
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"version": ""
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}
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},
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"nbformat": 4,
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"nbformat_minor": 2
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}
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