public Boolean ContainsValue(TValue key) { return(Reversed.ContainsKey(key)); }
public Boolean ContainsValue([NotNull] TValue value) { return(Reversed.ContainsKey(value)); }
public ImmutableMap <TKey, TValue> RemoveByValue(TValue key) { return(Reversed.ContainsKey(key) ? new ImmutableMap <TKey, TValue>(Base.Remove(Reversed[key]), Reversed.Remove(key)) : this); }