equals method

bool equals (dynamic e1, dynamic e2)
override

Compare two elements for being equal.

This should be a proper equality relation.

Implementation 

bool equals(e1, e2) {
  if (e1 is Set) {
    return e2 is Set && new SetEquality(this).equals(e1, e2);
  }
  if (e1 is Map) {
    return e2 is Map &&
        new MapEquality(keys: this, values: this).equals(e1, e2);
  }
  if (!_unordered) {
    if (e1 is List) {
      return e2 is List && new ListEquality(this).equals(e1, e2);
    }
    if (e1 is Iterable) {
      return e2 is Iterable && new IterableEquality(this).equals(e1, e2);
    }
  } else if (e1 is Iterable) {
    if (e1 is List != e2 is List) return false;
    return e2 is Iterable &&
        new UnorderedIterableEquality(this).equals(e1, e2);
  }
  return _base.equals(e1, e2);
}