docs: def build_GTK_KDE(self):
          """Build the Key Data Encapsulation for GTK
          KeyID: 0
          Ref: 802.11i p81
          """
          return b''.join([
              b'\xdd',  # Type KDE
              chb(len(self.gtk_full) + 6),
              b'\x00\x0f\xac',  # OUI
              b'\x01',  # GTK KDE
              b'\x00\x00',  # KeyID - Tx - Reserved x2
              self.gtk_full,
          ])