code: def __len__(self):
      return len(self._intersection)
  
imports: import xml.etree.ElementTree
  from icevision.imports import *
  from icevision.utils import *
  from icevision.core import *
  from icevision.parsers.parser import *
label_desc: Use image node_id 2 for calling the VOCMaskParser obj's underlying member method code with example usage: obj.__len__() and returns: len