from datetime import datetime


def time_to_str(time):
    """
    Returns the time represented by the parameter in the format of Boost's
    posix time `to_iso_string` function.

    :param time: integer POSIX time
    :type time: int

    :return: string in the form "YYYYMMDDTHHMMSS", where T is the date-time separator
    :rtype: str
    """
    dt = datetime.utcfromtimestamp(time)
    return dt.strftime("%Y%m%dT%H%M%S").encode("utf-8")