parameter method
Implementation
Parser<Node> parameter() =>
seq2(
ref0(atom),
seq3(
ref1(token, '('),
ref0(parameter)
.plusSeparated(ref1(token, ','))
.map((list) => list.elements),
ref1(token, ')'),
).map3((_, params, _) => params).optional(),
).map2(
(atom, params) => params == null ? atom : Term(atom.toString(), params),
);