import time


def readable_time(timestamp=None):
    """
    Return a human-friendly string of a timestamp

    e.g.
        timestamp: 1582029001.6709404
        readable time: Tue Feb 18 20:30:01 2020

    Args:
        timestamp: a UNIX timestamp

    Returns:
        str, a human-friendly readable string of the argument timestamp
    """
    time_readable_str = str(time.asctime(time.localtime(timestamp if timestamp else time.time())))
    return time_readable_str