code: def ssh_init_sec_context(
          self, target, desired_mech=None, username=None, recv_token=None
      ):
          
          from pyasn1.codec.der import decoder
  
          self._username = username
          self._gss_host = target
          error = 0
          targ_name = "host/" + self._gss_host
          if desired_mech is not None:
              mech, __ = decoder.decode(desired_mech)
              if mech.__str__() != self._krb5_mech:
                  raise SSHException("Unsupported mechanism OID.")
          try:
              if recv_token is None:
                  self._gss_ctxt = sspi.ClientAuth(
                      "Kerberos", scflags=self._gss_flags, targetspn=targ_name
                  )
              error, token = self._gss_ctxt.authorize(recv_token)
              token = token[0].Buffer
          except pywintypes.error as e:
              e.strerror += ", Target: {}".format(e, self._gss_host)
              raise
  
          if error == 0:
              """
              if the status is GSS_COMPLETE (error = 0) the context is fully
              established an we can set _gss_ctxt_status to True.
              """
              self._gss_ctxt_status = True
              token = None
              """
              You won't get another token if the context is fully established,
              so i set token to None instead of ""
              """
          return token
docs: Initialize a SSPI context.
  
          :param str username: The name of the user who attempts to login
          :param str target: The FQDN of the target to connect to
          :param str desired_mech: The negotiated SSPI mechanism
                                   ("pseudo negotiated" mechanism, because we
                                   support just the krb5 mechanism :-))
          :param recv_token: The SSPI token received from the Server
          :raises:
              `.SSHException` -- Is raised if the desired mechanism of the client
              is not supported
          :return: A ``String`` if the SSPI has returned a token or ``None`` if
                   no token was returned