def add_access_key_permissions(self, access_key_id, permissions):
        """
        Adds to the existing list of permissions on this key with the contents of this list.
        Will not remove any existing permissions or modify the remainder of the key.

        :param access_key_id: the 'key' value of the access key to add permissions to
        :param permissions: the new permissions to add to the existing list of permissions
        """
        # Get current state via HTTPS.
        current_access_key = self.get_access_key(access_key_id)

        # Copy and only change the single parameter.
        payload_dict = KeenApi._build_access_key_dict(current_access_key)

        # Turn into sets to avoid duplicates.
        old_permissions = set(payload_dict["permitted"])
        new_permissions = set(permissions)
        combined_permissions = old_permissions.union(new_permissions)
        payload_dict["permitted"] = list(combined_permissions)

        # Now just treat it like a full update.
        return self.update_access_key_full(access_key_id, **payload_dict)