_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.

def _del_attrib(element):
        '''_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.
        '''

        for tag in operation_tag, insert_tag, value_tag, key_tag:
            if element.get(tag):
                del element.attrib[tag]
        return element