Function combine::parser::item::token

pub fn token<I>(c: I::Item) -> Token<I> where
    I: Stream,
    I::Item: PartialEq, 

Parses a character and succeeds if the character is equal to c.

let result = token('!')
    .parse("!")
    .map(|x| x.0);
assert_eq!(result, Ok('!'));