def epoch_to_human_time(epoch_time):
    """Converts an epoch timestamp to human readable time.

    This essentially converts an output of get_current_epoch_time to an output
    of get_current_human_time

    Args:
        epoch_time: An integer representing an epoch timestamp in milliseconds.

    Returns:
        A time string representing the input time.
        None if input param is invalid.
    """
    if isinstance(epoch_time, int):
        try:
            d = datetime.datetime.fromtimestamp(epoch_time / 1000)
            return d.strftime("%m-%d-%Y %H:%M:%S ")
        except ValueError:
            return None