@staticmethod<EOL><INDENT>def _del_attrib(element):<DEDENT>
for tag in operation_tag, insert_tag, value_tag, key_tag:<EOL><INDENT>if element.get(tag):<EOL><INDENT>del element.attrib[tag]<EOL><DEDENT><DEDENT>return element<EOL>
_del_attrib

        Low-level api: Delete four attributes from an Element node if they
        exist: operation, insert, value and key.

        Parameters
        ----------

        element : `Element`
            The Element node needs to be looked at.

        Returns
        -------

        Element
            The Element node is returned after processing.