/// <summary>
/// Returns a dictionary with the same keys. The value for each key is
/// obtained by calling <c>func(key, this[key])</c>.
/// </summary>
/// <typeparam name="TValue1">The type of the values in the returned dictionary.</typeparam>
/// <param name="func">The function mapped.</param>
/// <returns>The resulting dictionary.</returns>
public TreeDictionary <TKey, TValue1, TComparer> Map <TValue1>(Func <TKey, TValue, TValue1> func)
{
if (Count == 0)
{
return(TreeDictionary <TKey, TValue1, TComparer> .Empty);
}
return(TreeDictionary <TKey, TValue1, TComparer> .Balanced(
_key, func(_key, _value), _left.Map(func), _right.Map(func)));
}