<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def data_json(self, extra_context=None, publish=False):
 """ Serve site context as JSON. Useful for debugging. """

        if not self.project.CREATE_JSON:
            # nothing to see here, but the right mimetype
            return jsonify()

        if not self.data:
            # this sets site.data by spreadsheet or gdoc
            self.get_context(publish)

        return jsonify(self.data)