|Given the key value of the desired item returns
its numeric 1-based index.
index = HandyCollection.GetItemIndex(key)
[id(9), helpstring("Gets index of item by its key")]
HRESULT GetItemIndex([in]VARIANT varKey, [out, retval] long* plIndex);
key - The key value used to find the desired item.
index - 1-based index of the serached item. If it wasn't found has value
Use this method to evaluate the item index in collection if you know its key.
If the item wan't found HRESULT is set to S_FALSE.