/// <summary>
/// Determines whether the <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the specified key.
/// </summary>
/// <returns>
/// true if the <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the key; otherwise, false.
/// </returns>
/// <param name="key">The key to locate in the <see cref="T:System.Collections.Generic.IDictionary`2" />.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="key" /> is null.</exception>
public bool ContainsKey(TKey key)
{
AVL_Node <Pair <TKey, TValue> > temp;
return(keyCollection.Contains(new Pair <TKey, TValue> {
Key = key
}, out temp));
}
