code: def get_global_step_var():
      
      scope = tfv1.VariableScope(reuse=False, name='')  # the root vs
      with tfv1.variable_scope(scope):
          var = tfv1.train.get_or_create_global_step()
      return var
docs: Returns:
          tf.Tensor: the global_step variable in the current graph. Create if doesn't exist.