L.insert(index, object) -- insert object before index

def insert(self, index, p_object):
        """ L.insert(index, object) -- insert object before index """
        key = self._get_object_key(p_object)
        if key in self._col_dict:
            raise KeyError()
        self._col_list.insert(index, p_object)
        self._col_dict[key] = p_object