token method
Implementation
Parser token(Object input) {
if (input is Parser) {
return input.token().trim();
} else if (input is String) {
return token(input.length == 1 ? char(input) : string(input));
} else if (input is _ParserFunc) {
return token(ref0(input));
}
throw ArgumentError.value(input, 'invalid token parser');
}