isVariable method
Implementation
bool isVariable(dynamic object) {
if (object == null) return false;
// this captures instances like a.set()
if (object is Variable) return true;
// this captures instances like GLOBAL.a.set()
String exp = object.toString();
if (object is MemberExpression &&
exp.contains(".") &&
!exp.contains("(") &&
!exp.contains("[")) return true;
return false;
}