Function hyper::http::is_token

pub fn is_token(b: u8) -> bool

Determines if byte is a token char.

token          = 1*tchar

tchar          = "!" / "#" / "$" / "%" / "&" / "'" / "*"
               / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"
               / DIGIT / ALPHA
               ; any VCHAR, except delimiters