def set_letter_literal_handle(self, tokens):
        """Process set literals."""
        if len(tokens) == 1:
            set_type = tokens[0]
            if set_type == "s":
                return "_coconut.set()"
            elif set_type == "f":
                return "_coconut.frozenset()"
            else:
                raise CoconutInternalException("invalid set type", set_type)
        elif len(tokens) == 2:
            set_type, set_items = tokens
            internal_assert(len(set_items) == 1, "invalid set literal item", tokens[0])
            if set_type == "s":
                return self.set_literal_handle([set_items])
            elif set_type == "f":
                return "_coconut.frozenset(" + set_to_tuple(set_items) + ")"
            else:
                raise CoconutInternalException("invalid set type", set_type)
        else:
            raise CoconutInternalException("invalid set literal tokens", tokens)
Process set literals.