On env-purge-doc, do callbacks

def call_purge_doc(cls, kb_app, sphinx_app: Sphinx,
                       sphinx_env: BuildEnvironment,
                       docname: str):
        """ On env-purge-doc, do callbacks """

        for callback in EventAction.get_callbacks(kb_app, SphinxEvent.EPD):
            callback(kb_app, sphinx_app, sphinx_env, docname)