<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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!")