expect method
Check current token and some tokens after it to see if the types
match,
return a boolean result.
If consume
is true, will advance.
Implementation
bool expect(List<String> types, {bool consume = false}) {
for (var i = 0; i < types.length; ++i) {
if (peek(i).type != types[i]) {
return false;
}
}
if (consume) {
advance(types.length);
}
return true;
}