public bool Contains(TK key)
{
return(_range.IsWithin(key) && _underlying.ContainsKey(key));
}
/// <summary>
/// Determines whether the <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the specified key.
/// </summary>
/// <param name="key">The key to locate in the <see cref="T:System.Collections.Generic.IDictionary`2" />.</param>
/// <returns>
/// true if the <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the key; otherwise, false.
/// </returns>
/// <exception cref="T:System.ArgumentNullException">
/// <paramref name="key" /> is null.
/// </exception>
public bool ContainsKey(TK key)
{
return(_range.IsWithin(key) && _parent.ContainsKey(key));
}
