def _validate_response(self, response):
        """ Ensures response from IEX server is valid.

        Parameters
        ----------
        response: requests.response
            A requests.response object

        Returns
        -------
        response: Parsed JSON
            A json-formatted response

        Raises
        ------
        ValueError
            If a single Share symbol is invalid
        IEXQueryError
            If the JSON response is empty or throws an error

        """
        if response.text == "Unknown symbol":
            raise IEXQueryError()
        try:
            json_response = response.json(
                parse_int=self.json_parse_int,
                parse_float=self.json_parse_float)
            if "Error Message" in json_response:
                raise IEXQueryError()
        except ValueError:
            raise IEXQueryError()
        return json_response