code: def unify_walk(v, o, U):
      """
      This simply checks if the Var has an unification in U and uses it
      instead of the Var. If the Var is already its tighest unification,
      falls through.
  
      """
      best_v = U[v]
      if v is not best_v:
          return unify_walk(
              o, best_v, U
          )  # reverse argument order so if o is a Variable this block of code is run again
      else:
          return FALL_THROUGH
  
imports: from __future__ import absolute_import, print_function, division
  from copy import copy
  from functools import partial
  from theano.gof.utils import ANY_TYPE, comm_guard, FALL_THROUGH, iteritems
label_desc: Use image node_id 16 for calling a global function with example usage: unify_walk(v, o, U) and returns: unify_walk, FALL_THROUGH