class_docstr: A node in grad_tree. A GradNode contains the op_optree and the grad_op_tree
  at this location of the grad_tree, and it also has pointers to the left and
  right child in the grad_tree.
class_docstr_tok: ["A","node","in","grad_tree",".","A","GradNode","contains","the","op_optree","and","the","grad_op_tree","at","this","location","of","the","grad_tree",",","and","it","also","has","pointers","to","the","left","and","right","child","in","the","grad_tree","."]
code: def __del__(self):
      self.cleanup()
  
imports: from __future__ import division
  from builtins import object, zip
  from neon.backends.backend import OpTreeNode, Tensor
  import numpy
  from functools import wraps
label_desc: Use image node_id 2 for calling the GradNode obj's underlying member method code with example usage: obj.__del__() without return types