feat: Rewrite try_from_into (#393)
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@ -17,6 +17,7 @@ struct Person {
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// 3. Extract the first element from the split operation and use it as the name
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// 4. If the name is empty, then return an error
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// 5. Extract the other element from the split operation and parse it into a `usize` as the age
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// with something like `"4".parse::<usize>()`.
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// If while parsing the age, something goes wrong, then return an error
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// Otherwise, then return a Result of a Person object
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impl FromStr for Person {
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@ -82,4 +83,4 @@ mod tests {
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",one".parse::<Person>().unwrap();
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}
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}
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}
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@ -5,98 +5,126 @@
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use std::convert::{TryInto, TryFrom};
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#[derive(Debug)]
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struct Person {
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name: String,
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age: usize,
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struct Color {
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red: u8,
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green: u8,
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blue: u8,
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}
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// I AM NOT DONE
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// Your task is to complete this implementation
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// in order for the line `let p = Person::try_from("Mark,20")` to compile
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// and return an Ok result of inner type Person.
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// Please note that you'll need to parse the age component into a `usize`
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// with something like `"4".parse::<usize>()`. The outcome of this needs to
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// be handled appropriately.
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// and return an Ok result of inner type Color.
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// You need create implementation for a tuple of three integer,
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// an array of three integer and slice of integer.
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//
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// Steps:
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// 1. If the length of the provided string is 0, then return an error
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// 2. Split the given string on the commas present in it
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// 3. Extract the first element from the split operation and use it as the name
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// 4. If the name is empty, then return an error.
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// 5. Extract the other element from the split operation and parse it into a `usize` as the age
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// If while parsing the age, something goes wrong, then return an error
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// Otherwise, then return a Result of a Person object
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impl TryFrom<&str> for Person {
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// Note, that implementation for tuple and array will be checked at compile-time,
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// but slice implementation need check slice length!
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// Also note, that chunk of correct rgb color must be integer in range 0..=255.
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// Tuple implementation
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impl TryFrom<(i16, i16, i16)> for Color {
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type Error = String;
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fn try_from(s: &str) -> Result<Self, Self::Error> {
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fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
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}
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}
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// Array implementation
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impl TryFrom<[i16; 3]> for Color {
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type Error = String;
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fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
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}
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}
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// Slice implementation
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impl TryFrom<&[i16]> for Color {
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type Error = String;
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fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
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}
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}
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fn main() {
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// Use the `from` function
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let p1 = Person::try_from("Mark,20");
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// Since From is implemented for Person, we should be able to use Into
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let p2: Result<Person, _> = "Gerald,70".try_into();
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println!("{:?}", p1);
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println!("{:?}", p2);
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let c1 = Color::try_from((183, 65, 14));
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println!("{:?}", c1);
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// Since From is implemented for Color, we should be able to use Into
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let c2: Result<Color, _> = [183, 65, 14].try_into();
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println!("{:?}", c2);
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let v = vec![183, 65, 14];
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// With slice we should use `from` function
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let c3 = Color::try_from(&v[..]);
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println!("{:?}", c3);
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// or take slice within round brackets and use Into
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let c4: Result<Color, _> = (&v[..]).try_into();
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println!("{:?}", c4);
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_bad_convert() {
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// Test that error is returned when bad string is provided
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let p = Person::try_from("");
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assert!(p.is_err());
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}
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#[test]
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fn test_good_convert() {
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// Test that "Mark,20" works
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let p = Person::try_from("Mark,20");
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assert!(p.is_ok());
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let p = p.unwrap();
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assert_eq!(p.name, "Mark");
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assert_eq!(p.age, 20);
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#[should_panic]
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fn test_tuple_out_of_range_positive() {
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let _ = Color::try_from((256, 1000, 10000)).unwrap();
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}
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#[test]
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#[should_panic]
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fn test_panic_empty_input() {
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let p: Person = "".try_into().unwrap();
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fn test_tuple_out_of_range_negative() {
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let _ = Color::try_from((-1, -10, -256)).unwrap();
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}
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#[test]
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#[should_panic]
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fn test_panic_bad_age() {
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let p = Person::try_from("Mark,twenty").unwrap();
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fn test_tuple_correct() {
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let c: Color = (183, 65, 14).try_into().unwrap();
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assert_eq!(c.red, 183);
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assert_eq!(c.green, 65);
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assert_eq!(c.blue, 14);
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}
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#[test]
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#[should_panic]
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fn test_missing_comma_and_age() {
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let _: Person = "Mark".try_into().unwrap();
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fn test_array_out_of_range_positive() {
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let _: Color = [1000, 10000, 256].try_into().unwrap();
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}
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#[test]
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#[should_panic]
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fn test_array_out_of_range_negative() {
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let _: Color = [-10, -256, -1].try_into().unwrap();
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}
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#[test]
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fn test_array_correct() {
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let c: Color = [183, 65, 14].try_into().unwrap();
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assert_eq!(c.red, 183);
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assert_eq!(c.green, 65);
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assert_eq!(c.blue, 14);
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}
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#[test]
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#[should_panic]
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fn test_missing_age() {
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let _: Person = "Mark,".try_into().unwrap();
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fn test_slice_out_of_range_positive() {
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let arr = [10000, 256, 1000];
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let _ = Color::try_from(&arr[..]).unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_name() {
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let _ : Person = ",1".try_into().unwrap();
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fn test_slice_out_of_range_negative() {
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let arr = [-256, -1, -10];
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let _ = Color::try_from(&arr[..]).unwrap();
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}
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#[test]
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fn test_slice_correct() {
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let v = vec![183, 65, 14];
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let c = Color::try_from(&v[..]).unwrap();
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assert_eq!(c.red, 183);
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assert_eq!(c.green, 65);
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assert_eq!(c.blue, 14);
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}
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#[test]
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#[should_panic]
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fn test_missing_name_and_age() {
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let _: Person = ",".try_into().unwrap();
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fn test_slice_excess_length() {
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let v = vec![0, 0, 0, 0];
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let _ = Color::try_from(&v[..]).unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_name_and_invalid_age() {
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let _: Person = ",one".try_into().unwrap();
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}
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}
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}
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@ -799,5 +799,6 @@ name = "from_str"
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path = "exercises/conversions/from_str.rs"
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mode = "test"
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hint = """
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If you've already solved try_from_into.rs, then this is almost a copy-paste.
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Otherwise, go ahead and solve try_from_into.rs first."""
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The implementation of FromStr should return an Ok with a Person object,
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or an Err with a string if the string is not valid.
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This is a some like an `try_from_into` exercise."""
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