Update a dash meta and content, return updated dash content.

        Args:
            dash_id: dashboard id.

        Returns:
            A dict containing the updated content of that dashboard, not include the meta info.

def put(self, dash_id=0):
        """Update a dash meta and content, return updated dash content.

        Args:
            dash_id: dashboard id.

        Returns:
            A dict containing the updated content of that dashboard, not include the meta info.
        """
        data = request.get_json()
        updated = self._update_dash(dash_id, data)
        return build_response(dict(data=updated, code=200))