code: def _check_write_permission(self, res, depth, environ):
          
          lockMan = self._davProvider.lock_manager
          if lockMan is None or res is None:
              return True
  
          refUrl = res.get_ref_url()
  
          if "wsgidav.conditions.if" not in environ:
              util.parse_if_header_dict(environ)
  
          # raise HTTP_LOCKED if conflict exists
          lockMan.check_write_permission(
              refUrl,
              depth,
              environ["wsgidav.ifLockTokenList"],
              environ["wsgidav.user_name"],
          )
docs: Raise DAVError(HTTP_LOCKED), if res is locked.
  
          If depth=='infinity', we also raise when child resources are locked.