code: def initialize_root(self):
      self.parents = []
      self.vjp = lambda g: ()
  
imports: from itertools import count
  from functools import reduce
  from .tracer import trace, primitive, toposort, Node, Box, isbox, getval
  from .util import func, subval
  import warnings
label_desc: Use image node_id 2 for calling the VJPNode obj's underlying member method code with example usage: obj.initialize_root() without return types