invert method

@useResult Map<V, K> invert()

Inverts keys and values. On duplicate values, last key wins.

Implementation

@useResult
Map<V, K> invert() {
  final Map<V, K> out = <V, K>{};
  for (final MapEntry<K, V> e in entries) {
    out[e.value] = e.key;
  }
  return out;
}