
  -type deprecated_time_unit() ::
            seconds | milli_seconds | micro_seconds | nano_seconds.

  The time_unit() type also consist of the following deprecated
  symbolic time units:

  seconds:
    Same as second.

  milli_seconds:
    Same as millisecond.

  micro_seconds:
    Same as microsecond.

  nano_seconds:
    Same as nanosecond.
