/// <summary>Determines whether the dictionary contains the supplied value.</summary> /// <param name="value">The value to locate.</param> /// <returns><b>true</b> if <em>value</em> is contained in the dictionary; otherwise <b>false</b>.</returns> /// <remarks>This is a O(<em>n</em>) operation.</remarks> bool ICollection <TValue> .Contains(TValue value) => tree.ContainsValue2(value) >= 0;
