docs: def set_query(self, value):
          """ Convert a dict form of query in a string of needed and store the query string.
  
              Args:
                  value -- A query string or a dict with query xpaths as keys and text or
                          nested query dicts as values.
          """
          if isinstance(value, basestring) or value is None:
              self._content['query'] = value
          elif hasattr(value, 'keys'):
              self._content['query'] = query.terms_from_dict(value)
          else:
              raise TypeError("Query must be a string or dict. Got: " + type(value) + " insted!")