code: def ssh_accept_sec_context(self, hostname, username, recv_token):
          
          self._gss_host = hostname
          self._username = username
          targ_name = "host/" + self._gss_host
          self._gss_srv_ctxt = sspi.ServerAuth("Kerberos", spn=targ_name)
          error, token = self._gss_srv_ctxt.authorize(recv_token)
          token = token[0].Buffer
          if error == 0:
              self._gss_srv_ctxt_status = True
              token = None
          return token
docs: Accept a SSPI context (server mode).
  
          :param str hostname: The servers FQDN
          :param str username: The name of the user who attempts to login
          :param str recv_token: The SSPI Token received from the server,
                                 if it's not the initial call.
          :return: A ``String`` if the SSPI has returned a token or ``None`` if
                   no token was returned