equals method
Implementation
@override
FutureOr<bool> equals(Object other) async {
if (identical(this, other)) return true;
if (other is ASTValueFuture) {
var v1 = await future;
var v2 = await other.future;
return v1 == v2;
} else if (other is ASTValue) {
var context = VMContext.getCurrent()!;
var v1 = await future;
var v2 = await other.getValue(context);
return v1 == v2;
}
return super == (other);
}