code: def setup_graph(self):
          
          all_vars = tfv1.global_variables() + tfv1.local_variables()
          for v in all_vars:
              if v.name == self.var_name:
                  self.var = v
                  break
          else:
              raise ValueError("{} is not a variable in the graph!".format(self.var_name))
docs: Will setup the assign operator for that variable.