Create a comment on the request.
        :param request_id: the id of the request
        :param body: the comment body
        :param commit: which commit to comment on
        :param filename: which file to comment on
        :param row: which line of code to comment on
        :return:

def comment_request(self, request_id, body, commit=None,
                        filename=None, row=None):
        """
        Create a comment on the request.
        :param request_id: the id of the request
        :param body: the comment body
        :param commit: which commit to comment on
        :param filename: which file to comment on
        :param row: which line of code to comment on
        :return:
        """
        request_url = ("{}pull-request/{}/comment"
                       .format(self.create_basic_url(), request_id))

        payload = {'comment': body}
        if commit is not None:
            payload['commit'] = commit
        if filename is not None:
            payload['filename'] = filename
        if row is not None:
            payload['row'] = row

        return_value = self._call_api(request_url,
                                      method='POST', data=payload)

        LOG.debug(return_value)