import time


def convert_to_timestamp(seconds):
    """
    Converts an integer into a string 'HH:MM:SS'.
    We differ a bit from python's standard time library
    in that if a number is negative, instead of reversing
    back into the 24hr mark, we return 00:00:00.
    """
    if seconds < 0:
        return '0:00'

    tt = time.strftime('%H:%M:%S', time.gmtime(seconds))
    if tt[:2] == '00':
        tt = tt[3:]  # slice off leading ':' also
    if tt[:1] == '0':
        tt = tt[1:]
    return tt