def METHOD_NAME(self):
    """Return the **binary** (non-printable) digest of the message that has been hashed so far.
    :return: The hash digest, computed over the data processed so far.
             Binary form.
    :rtype: byte string
    """
    self._digest_done = True
    bfr = create_string_buffer(self.digest_size)
    result = _raw_keccak_lib.keccak_digest(self._state.get(),
                                           bfr,
                                           c_size_t(self.digest_size),
                                           c_ubyte(self._padding))
    if result:
        raise ValueError("Error %d while instantiating SHA-3/512"
                         % result)
    self._digest_value = get_raw_buffer(bfr)
    return self._digest_value