code: def parser(cls, buf, offset):
          
          match = OFPMatch()
          type_, length = struct.unpack_from('!HH', buf, offset)
  
          match.type = type_
          match.length = length
  
          # ofp_match adjustment
          offset += 4
          length -= 4
  
          fields = []
          while length > 0:
              n, value, mask, field_len = ofproto.oxm_parse(buf, offset)
              k, uv = ofproto.oxm_to_user(n, value, mask)
              fields.append((k, uv))
              offset += field_len
              length -= field_len
          match._fields2 = fields
          return match
docs: Returns an object which is generated from a buffer including the
          expression of the wire protocol of the flow match.