Linked List in rust

llist3.rs

struct Node {
    value: i64,
    next: Option<Box<Node>>,
}

struct List {
    head: Option<Box<Node>>,
}

impl List {
    fn new() -> List {	
	List{head: None}
    }

    fn push(&mut self, value: i64) {
	let mut head = self.head.take();
	let mut newHead = Node{value: value, next: head};
	self.head = Some(Box::new(newHead));
    }

    fn pop(&mut self) -> Option<i64> {
	match self.head {
	    None => None,
	    Some(_) => {
		let mut v = self.head.take().unwrap();
		let value = v.value;
		self.head = v.next;
		return Some(value);
	    }
	}
    }
}


fn main() -> () {
    let mut l : List = List::new();
    l.push(10);
    l.push(20);
    l.push(30);
    l.push(40);

    println!("{}", l.pop().unwrap());
    println!("{}", l.pop().unwrap());
    println!("{}", l.pop().unwrap());
    println!("{}", l.pop().unwrap());
}