How to use the pysodium.crypto_generichash function in pysodium

r=pysodium.crypto_generichash(b'howdy')
        pysodium.crypto_generichash(b'howdy', outlen=4)
        r6=pysodium.crypto_generichash(b'howdy', outlen=6)
        pysodium.crypto_generichash(b'howdy', outlen=8)
        state = pysodium.crypto_generichash_init()
        pysodium.crypto_generichash_update(state, b'howdy')
        r1=pysodium.crypto_generichash_final(state)

        state = pysodium.crypto_generichash_init(outlen=6)
        pysodium.crypto_generichash_update(state, b'howdy')
        r61=pysodium.crypto_generichash_final(state, outlen=6)
        self.assertEqual(r, r1)
        self.assertEqual(r6, r61)

        self.assertNotEqual(pysodium.crypto_generichash( 'salt0'), pysodium.crypto_generichash( 'salt1'))
        self.assertNotEqual(pysodium.crypto_generichash(b'salt0'), pysodium.crypto_generichash(b'salt1'))

ensure_self_specified(opts)
        ensure_dhpeers_specified(opts)
        ensure_name_specified(opts)
        sec = mpecdh_start_handler(opts.name, opts.dh_peers, opts.self, opts.infile, opts.outfile, opts.basedir)
        if sec:
            print >>sys.stderr, "[pbp] pushed shared secret, hash", b85encode(nacl.crypto_generichash(sec, outlen=6))
            clearmem(sec)
            sec = None

    # finish MPECDH
    elif opts.action=='de':
        ensure_self_specified(opts)
        ensure_name_specified(opts)
        sec = mpecdh_end_handler(opts.name, opts.self, opts.infile, opts.outfile, opts.basedir)
        if sec:
            print >>sys.stderr, "[pbp] pushed shared secret, hash", b85encode(nacl.crypto_generichash(sec, outlen=6))
            clearmem(sec)
            sec = None

    elif opts.action=='R':
        ensure_size_good(opts)
        if PITCHFORK and opts.PITCHFORK:
            pitchfork.init()
            pitchfork.rng(int(opts.size), opts.outfile)
        else:
            random_stream_handler(opts.outfile, opts.size)

    elif opts.action=='h':
        hsum = hash_handler(opts.infile, k=load_key(opts.key), outlen=int(opts.size or '16'))
        if hsum:
            print ' '.join(split_by_n(binascii.hexlify(hsum),4))

def doSphinx(self, message, host, b, cb):
    self.hostid=pysodium.crypto_generichash(host, self.getsalt(), 32)
    signed=pysodium.crypto_sign(message,self.getkey())
    loop = asyncio.get_event_loop()
    coro = loop.create_connection(lambda: SphinxClientProtocol(signed, loop, b, self, cb), address, port)
    try:
      loop.run_until_complete(coro)
      loop.run_forever()
    except:
      raise

def list(self, host):
    salt = self.getsalt()
    hostid = pysodium.crypto_generichash(host, salt, 32)
    return self.getusers(hostid) or []

def getid(self, host, user):
    salt = self.getsalt()
    return pysodium.crypto_generichash(b''.join((user.encode(),host.encode())), salt, 32)

def new_event(self, d, p):
        """Create a new event (and also return it's hash)."""

        assert p == () or len(p) == 2                   # 2 parents
        assert p == () or self.hg[p[0]].c == self.pk  # first exists and is self-parent
        assert p == () or self.hg[p[1]].c != self.pk  # second exists and not self-parent
        # TODO: fail if an ancestor of p[1] from creator self.pk is not an
        # ancestor of p[0]

        t = time()
        s = crypto_sign_detached(dumps((d, p, t, self.pk)), self.sk)
        ev = Event(d, p, t, self.pk, s)

        return crypto_generichash(dumps(ev)), ev

def is_valid_event(self, h, ev):
        try:
            crypto_sign_verify_detached(ev.s, dumps(ev[:-1]), ev.c)
        except ValueError:
            return False

        return (crypto_generichash(dumps(ev)) == h
                and (ev.p == ()
                     or (len(ev.p) == 2
                         and ev.p[0] in self.hg and ev.p[1] in self.hg
                         and self.hg[ev.p[0]].c == ev.c
                         and self.hg[ev.p[1]].c != ev.c)))