internal static IDictionary <TKey, TValue> ToBuilder <TKey, TValue>(this IImmutableDictionary <TKey, TValue> dictionary)
where TKey : notnull
{
return(dictionary switch
{
ImmutableDictionary <TKey, TValue> d => d.ToBuilder(),
ImmutableSortedDictionary <TKey, TValue> d => d.ToBuilder(),
ImmutableSegmentedDictionary <TKey, TValue> d => d.ToBuilder(),
null => throw new ArgumentNullException(nameof(dictionary)),
_ => throw ExceptionUtilities.UnexpectedValue(dictionary),
});