code: def cache_entry(self):
          
          if self.storage_path is None:
              raise ValueError('This file is temporary and so a lal '
                               'cache entry cannot be made')
  
          file_url = urlparse.urlunparse(['file', 'localhost', self.storage_path, None,
                                              None, None])
          cache_entry = lal.utils.CacheEntry(self.ifo_string,
                     self.tagged_description, self.segment_list.extent(), file_url)
          cache_entry.workflow_file = self
          return cache_entry
docs: Returns a CacheEntry instance for File.