## ownership

### Instruction

- Create a function that takes ownership of a string and returns the first sub-word in it

- It should work for `camelCase` as well as `snake_case`

### Expected Function

```rust
pub fn first_subword(mut s: String) -> String {
}
```

### Usage

Here is a program to test your function

```rust
fn main() {
	let s1 = String::from("helloWorld");
	let s2 = String::from("snake_case");
	let s3 = String::from("CamelCase");
	let s4 = String::from("just");

	println!("first_subword({}) = {}", s1.clone(), first_subword(s1)); 
	println!("first_subword({}) = {}", s2.clone(), first_subword(s2));
	println!("first_subword({}) = {}", s3.clone(), first_subword(s3));
	println!("first_subword({}) = {}", s4.clone(), first_subword(s4));
}
```

And its output

```console
student@ubuntu:~/[[ROOT]]/test$ cargo run
first_subword(helloWorld) = hello
first_subword(snake_case) = snake
first_subword(CamelCase) = Camel
first_subword(just) = just
student@ubuntu:~/[[ROOT]]/test$
```