directly into the provided
        buffer, rather than creating a new string.

        :param buffer: The buffer to copy into.
        :param nbytes: (optional) The maximum number of bytes to read into the
            buffer. If not present, defaults to the size of the buffer. If
            larger than the size of the buffer, is reduced to the size of the
            buffer.
        :param flags: (optional) The only supported flag is ``MSG_PEEK``,
            all other flags are ignored.
        :return: The number of bytes read into the buffer.
        Nr