code: def _parse_kexgss_group(self, m):
          
          self.p = m.get_mpint()
          self.g = m.get_mpint()
          # reject if p's bit length < 1024 or > 8192
          bitlen = util.bit_length(self.p)
          if (bitlen < 1024) or (bitlen > 8192):
              raise SSHException(
                  "Server-generated gex p (don't ask) is out of range "
                  "({} bits)".format(bitlen)
              )
          self.transport._log(
              DEBUG, "Got server p ({} bits)".format(bitlen)
          )  # noqa
          self._generate_x()
          # now compute e = g^x mod p
          self.e = pow(self.g, self.x, self.p)
          m = Message()
          m.add_byte(c_MSG_KEXGSS_INIT)
          m.add_string(self.kexgss.ssh_init_sec_context(target=self.gss_host))
          m.add_mpint(self.e)
          self.transport._send_message(m)
          self.transport._expect_packet(
              MSG_KEXGSS_HOSTKEY,
              MSG_KEXGSS_CONTINUE,
              MSG_KEXGSS_COMPLETE,
              MSG_KEXGSS_ERROR,
          )
docs: Parse the SSH2_MSG_KEXGSS_GROUP message (client mode).
  
          :param `Message` m: The content of the SSH2_MSG_KEXGSS_GROUP message