@Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;

    MutualMap mutualMap = (MutualMap)o;
    return myKey2Value.equals(mutualMap.myKey2Value) && myValue2Key.equals(mutualMap.myValue2Key);
  }
@Override
  public boolean equals(Object o)