code: def _get_vlan_length(buff):
          
          length = 0
          begin = 12
  
          while(buff[begin:begin+2] in (EtherType.VLAN.to_bytes(2, 'big'),
                                        EtherType.VLAN_QINQ.to_bytes(2, 'big'))):
              length += 4
              begin += 4
  
          return length
docs: Return the total length of VLAN tags in a given Ethernet buffer.