code: def encrypt(self, orig_pkt, assoclen=None):
          
          hdr = copy.deepcopy(orig_pkt)
          del hdr[MACsec].payload
          del hdr[MACsec].type
          pktlen = len(orig_pkt)
          if self.send_sci:
              hdrlen = NOSCI_LEN + SCI_LEN
          else:
              hdrlen = NOSCI_LEN
          if assoclen is None or not self.do_encrypt:
              if self.do_encrypt:
                  assoclen = hdrlen
              else:
                  assoclen = pktlen
          iv = self.make_iv(orig_pkt)
          assoc, pt, _ = MACsecSA.split_pkt(orig_pkt, assoclen)
          encryptor = Cipher(
              algorithms.AES(self.key),
              modes.GCM(iv),
              backend=default_backend()
          ).encryptor()
          encryptor.authenticate_additional_data(assoc)
          ct = encryptor.update(pt) + encryptor.finalize()
          hdr[MACsec].payload = Raw(assoc[hdrlen:assoclen] + ct + encryptor.tag)
          return hdr
docs: encrypt a MACsec frame for this Secure Association