>>-removeItem(item-+--------+-)--------------------------------><
                   +-,index-+

If index is not specified, returns and removes from a relation the member item item. If the relation contains item associated with more than one index, the item returned and removed is unspecified.

If index is specified, returns and removes the member item item associated with index index. If item is the only member with index, then the index is also removed from the Relation.

Returns the Nil object if item is not a member item (associated with index index, if specified).