Perform POST /rooms/$room_id/ban

        Args:
            room_id (str): The room ID
            user_id (str): The user ID of the banee(sic)
            reason (str): The reason for this ban

def ban_user(self, room_id, user_id, reason=""):
        """Perform POST /rooms/$room_id/ban

        Args:
            room_id (str): The room ID
            user_id (str): The user ID of the banee(sic)
            reason (str): The reason for this ban
        """
        body = {
            "user_id": user_id,
            "reason": reason
        }
        return self._send("POST", "/rooms/" + room_id + "/ban", body)