code: def update(self):
      self._compute_new_pad_values()
      # insert a new constant for pad val, JUST before the op
      with self.op.enclosing_block:
          new_pad_var = mb.const(
              val=self.pad_amounts_new,
              mode="immediate_value",
              before_op=self.op,
          )
      self.op.enclosing_block.replace_uses_of_var_after_op(
          anchor_op=new_pad_var.op,
          end_op=self.op,
          old_var=self.pad_var,
          new_var=new_pad_var,
          no_check_var_types=True,
      )
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  from coremltools.converters.mil.mil.passes.pass_registry import register_pass
  from coremltools.converters.mil.mil import Builder
  from coremltools.converters.mil.mil.var import Var
  import logging
  import numpy
  import copy
  from collections import defaultdict
label_desc: Use image node_id 4 for calling the transform_pad obj's underlying member method code with example usage: obj.update() without return types