code: def _decode_relation(self, s):
          '''(INTERNAL) Decodes a relation line.
  
          The relation declaration is a line with the format ``@RELATION
          <relation-name>``, where ``relation-name`` is a string. The string must
          start with alphabetic character and must be quoted if the name includes
          spaces, otherwise this method will raise a `BadRelationFormat` exception.
  
          This method must receive a normalized string, i.e., a string without
          padding, including the "\r\n" characters.
  
          :param s: a normalized string.
          :return: a string with the decoded relation name.
          '''
          _, v = s.split(' ', 1)
          v = v.strip()
  
          if not _RE_RELATION.match(v):
              raise BadRelationFormat()
  
          res = unicode(v.strip('"\''))
          return ref _decode_relation(self, s):
          '''(INTERNAL) Decodes a relation line.
  
          The relation declaration is a line with the format ``@RELATION
          <relation-name>``, where ``relation-name`` is a string. The string must
          start with alphabetic character and must be quoted if the name includes
          spaces, otherwise this method will raise a `BadRelationFormat` exception.
  
          This method must receive a normalized string, i.e., a string without
          padding, including the "\r\n" characters.
  
          :param s: a normalized string.
          :return: a string with the decoded relation name.
          '''
          _, v = s.split(' ', 1)
          v = v.strip()
  
          if not _RE_RELATION.match(v):
              raise BadRelationFormat()
  
          res = unicode(v.strip('"\''))
          return res
docs: (INTERNAL) Decodes a relation line.
  
          The relation declaration is a line with the format ``@RELATION
          <relation-name>``, where ``relation-name`` is a string. The string must
          start with alphabetic character and must be quoted if the name includes
          spaces, otherwise this method will raise a `BadRelationFormat` exception.
  
          This method must receive a normalized string, i.e., a string without
          padding, including the "\r\n" characters.
  
          :param s: a normalized string.
          :return: a string with the decoded relation name.