code: def clear(self):
          
          vname = self.varname
          if self.path.exists():
              logger.debug('deleting cached work: {}'.format(self.path))
              self.path.unlink()
          if self.owner is not None and hasattr(self.owner, vname):
              logger.debug('removing instance var: {}'.format(vname))
              delattr(self.owner, vname)
          self.clear_global()
docs: Clear the data, and thus, force it to be created on the next fetch.  This is
          done by removing the attribute from ``owner``, deleting it from globals
          and removing the file from the disk.