pub fn tokens<C, E, T, Input>(
    cmp: C,
    expected: E,
    tokens: T,
) -> Tokens<C, E, T, Input>Expand description
Parses multiple tokens.
Consumes items from the input and compares them to the values from tokens using the
comparison function cmp. Succeeds if all the items from tokens are matched in the input
stream and fails otherwise with expected used as part of the error.
let result = tokens(|l, r| l.eq_ignore_ascii_case(&r), "abc", "abc".chars())
    .parse("AbC")
    .map(|x| x.0.as_str());
assert_eq!(result, Ok("abc"));
let result = tokens(
    |&l, r| (if l < r { r - l } else { l - r }) <= 2,
    error::Range(&b"025"[..]),
    &b"025"[..]
)
    .parse(&b"123"[..])
    .map(|x| x.0);
assert_eq!(result, Ok(&b"025"[..]));