Decorates a function with args so it can be used within an arg_scope.

  Args:
    func: function to decorate.

  Returns:
    A tuple with the decorated function func_with_args().

def add_arg_scope(func):
  """Decorates a function with args so it can be used within an arg_scope.

  Args:
    func: function to decorate.

  Returns:
    A tuple with the decorated function func_with_args().
  """
  @functools.wraps(func)
  def func_with_args(*args, **kwargs):
    current_scope = _current_arg_scope()
    current_args = kwargs
    key_func = (func.__module__, func.__name__)
    if key_func in current_scope:
      current_args = current_scope[key_func].copy()
      current_args.update(kwargs)
    return func(*args, **current_args)
  _add_op(func)
  return func_with_args