def _merge_slowly(self, other_trajectory, rename_dict):
for other_key in rename_dict:<EOL><INDENT>new_key = rename_dict[other_key]<EOL>other_instance = other_trajectory.f_get(other_key)<EOL>if other_instance.f_is_empty():<EOL><INDENT>with self._nn_interface._disable_logging:<EOL><INDENT>other_trajectory.f_load_item(other_instance)<EOL><DEDENT><DEDENT>if not self.f_contains(new_key):<EOL><INDENT>class_name = other_instance.f_get_class_name()<EOL>class_ = self._create_class(class_name)<EOL>my_instance = self.f_add_leaf(class_, new_key)<EOL><DEDENT>else:<EOL><INDENT>my_instance = self.f_get(new_key, shortcuts=False)<EOL><DEDENT>if not my_instance.f_is_empty():<EOL><INDENT>raise RuntimeError('<STR_LIT>' % new_key)<EOL><DEDENT>load_dict = other_instance._store()<EOL>my_instance._load(load_dict)<EOL>my_instance.f_set_annotations(**other_instance.v_annotations.f_to_dict(copy=False))<EOL>my_instance.v_comment = other_instance.v_comment<EOL>self.f_store_item(my_instance)<EOL>if other_instance.v_is_parameter:<EOL><INDENT>other_instance.f_unlock()<EOL>my_instance.f_unlock()<EOL><DEDENT>other_instance.f_empty()<EOL>my_instance.f_empty()<EOL><DEDENT>
Merges trajectories by loading iteratively items of the other trajectory and
        store it into the current trajectory.

        :param rename_dict:

            Dictionary containing mappings from the old result names in the `other_trajectory`
            to the new names in the current trajectory.