<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def _ssweek_to_gregorian(ssweek_year, ssweek_week, ssweek_day):
    "Gregorian calendar date for the given Sundaystarting-week year, week and day"
    year_start = _ssweek_year_start(ssweek_year)
    return year_start + dt.timedelta(days=ssweek_day-1, weeks=ssweek_week-1)