import time


def now() -> float:
    return int(time.time())


def singular_or_plural(num: float, singular: str, plural: str) -> str:
    if num == 1:
        return singular

    return plural


def time_ago(start_time: float, end_time: float) -> str:
    diff = end_time - start_time
    seconds = int(diff)

    if seconds < 60:
        word = singular_or_plural(seconds, "second", "seconds")
        return f"{seconds} {word} ago"

    minutes = seconds // 60

    if minutes < 60:
        word = singular_or_plural(minutes, "minute", "minutes")
        return f"{minutes} {word} ago"

    hours = minutes / 60

    if hours < 24:
        word = singular_or_plural(hours, "hour", "hours")
        return f"{hours:.1f} {word} ago"

    days = hours / 24

    if days < 30:
        word = singular_or_plural(days, "day", "days")
        return f"{days:.1f} {word} ago"

    months = days / 30

    if months < 12:
        word = singular_or_plural(months, "month", "months")
        return f"{months:.1f} {word} ago"

    years = months / 12
    word = singular_or_plural(years, "year", "years")
    return f"{years:.1f} {word} ago"