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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def query( # type: ignore self, url: Union[str, methods], data: Optional[MutableMapping] = None, headers: Optional[MutableMapping] = None, as_json: Optional[bool] = None, ) -> dict: """ Query the slack API When using :class:`slack.methods` the request is made `as_json` if available Args: url: :class:`slack.methods` or url string data: JSON encodable MutableMapping headers: Custom headers as_json: Post JSON to the slack API Returns: dictionary of slack API response data """

        url, body, headers = sansio.prepare_request(
            url=url,
            data=data,
            headers=headers,
            global_headers=self._headers,
            token=self._token,
        )
        return self._make_query(url, body, headers)