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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 months_ago(date, nb_months=1):
 """ Return the given `date` with `nb_months` substracted from it. """

    nb_years = nb_months // 12
    nb_months = nb_months % 12

    month_diff = date.month - nb_months

    if month_diff > 0:
        new_month = month_diff
    else:
        new_month = 12 + month_diff
        nb_years += 1

    return date.replace(day=1, month=new_month, year=date.year - nb_years)