/// Return the length (number of elements) of the given list.
Return the length (number of elements) of the given list.
Return the length ( number of elements ) of the given list .
pub fn len(self) -> usize {
        let mut node = self;
        let mut len = 0;
        while let Cons(&(_, next)) = node {
            node = next;
            len += 1;
        }
        len
    }
pub fn len ( self ) -> usize { let mut node = self ; let mut len = 0 ; while let Cons ( & ( _ , next ) ) = node { node = next ; len += 1 ; } len }
Return the length (number of elements) of the given list.
Return the length ( number of elements ) of the given list .
self