<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_vlan_length(buff):
 """Return the total length of VLAN tags in a given Ethernet buffer."""

        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