Pause the timer, preventing subsequent time from accumulating in the
    total.  Renders the timer inactive, disabling other timing commands.

    Returns:
        float: The current time.

    Raises:
        PausedError: If timer already paused.
        StoppedError: If timer already stopped.

def pause():
    """
    Pause the timer, preventing subsequent time from accumulating in the
    total.  Renders the timer inactive, disabling other timing commands.

    Returns:
        float: The current time.

    Raises:
        PausedError: If timer already paused.
        StoppedError: If timer already stopped.
    """
    t = timer()
    if f.t.stopped:
        raise StoppedError("Cannot pause stopped timer.")
    if f.t.paused:
        raise PausedError("Timer already paused.")
    f.t.paused = True
    f.t.tmp_total += t - f.t.start_t
    f.t.start_t = None
    f.t.last_t = None
    return t