docs: def hash_host(hostname, salt=None):
          """
          Return a "hashed" form of the hostname, as used by OpenSSH when storing
          hashed hostnames in the known_hosts file.
  
          :param str hostname: the hostname to hash
          :param str salt: optional salt to use when hashing (must be 20 bytes long)
          :return: the hashed hostname as a `str`
          """
          if salt is None:
              salt = os.urandom(sha1().digest_size)
          else:
              if salt.startswith('|1|'):
                  salt = salt.split('|')[2]
              salt = decodebytes(b(salt))
          assert len(salt) == sha1().digest_size
          hmac = HMAC(salt, b(hostname), sha1).digest()
          hostkey = '|1|%s|%s' % (u(encodebytes(salt)), u(encodebytes(hmac)))
          return hostkey.replace('\n', '')