Specifies the type of the function passed to foreach_remove.
It is called with each key/value pair, together with the user_data parameter passed to
foreach_remove. It should return
true if the key/value pair should be removed from the GenericSet.
| key |
a key |
| value |
the value associated with the key |
| user_data |
user data passed to remove |
|
true if the key/value pair should be removed from the GenericSet |