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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _iso_info(iso_year, iso_week):
    "Give all the iso info we need from one calculation"
    prev_year_start = _iso_year_start(iso_year-1)
    year_start = _iso_year_start(iso_year)
    next_year_start = _iso_year_start(iso_year+1)
    first_day = year_start + dt.timedelta(weeks=iso_week-1)
    last_day = first_day + dt.timedelta(days=6)
    prev_year_num_weeks = ((year_start - prev_year_start).days) // 7
    year_num_weeks = ((next_year_start - year_start).days) // 7
    return (first_day, last_day, prev_year_num_weeks, year_num_weeks)