Method empty

src/common/MemoryStreams.hpp:89–89

	size_t read_some(void *data, size_t size) override;
	size_t size() const { return in->size() - in_position; }
	bool empty() const { return size() == 0; }

	size_t copy_to(IOutputStream &out, size_t max_count = std::numeric_limits<size_t>::max());