|Appends the given item to collection and
assigns it the specified key value. You can later use the key value to index the item in
index = HandyCollection.Add(key, item)
[id(1), helpstring("Adds item to the collection")]
HRESULT Add([in] VARIANT varKey,[in] VARIANT varItem,[out,retval] VARIANT* pvarPlace);
key - the value assigned as key of that item in collection and later
used for indexing. Should be unique in collection.
item - Item being added to collection.
index - 1-based index of the item in collection.
If key parameter is already used in collection the item is not added and index has a
value of 0. S_FALSE is returned in HRESULT. Use another key in that case.