The __delslice__ method
__delslice__(self, i, j)
Called to implement deletion of
self[i:j]. Same notes for i and j
as for __getslice__. This method is deprecated. If no
__delslice__ is found, or for extended slicing of the form
self[i:j:k], a slice object is created, and passed to
__delitem__, instead of __delslice__ being called.