docs: def _format_device(var):
    """Returns the device with an annotation specifying `ResourceVariable`.
  
    "legacy" means a normal tf.Variable while "resource" means a ResourceVariable.
  
    For example:
    `(legacy)`
    `(resource)`
    `/job:learner/task:0/device:CPU:* (legacy)`
    `/job:learner/task:0/device:CPU:* (resource)`
  
    Args:
      var: The Tensorflow Variable to print.
    """
    if var.dtype.name.endswith("_ref"):
      resource_var_annotation = "(legacy)"
    else:
      resource_var_annotation = "(resource)"
  
    if var.device:
      return "{} {}".format(var.device, resource_var_annotation)
    else:
      return resource_var_annotation