docs: def get_name(self, type_, id_):
          """
          Read a cached name if available.
  
          :param type_: str, "owner" or "tag"
          :param id_: int, eg. 123456
          :returns: str, or None
          """
          cachefile = self.filename(type_, id_)
          try:
              with open(cachefile, 'r') as f:
                  return f.read()
          except (OSError, IOError) as e:
              if e.errno != errno.ENOENT:
                  raise