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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 is_outlier(df, item_id, segment_id, price):
 """ Verify if a item is an outlier compared to the other occurrences of the same item, based on his price. Args: item_id: idPlanilhaItens segment_id: idSegmento price: VlUnitarioAprovado """


    if (segment_id, item_id) not in df.index:
        return False

    mean = df.loc[(segment_id, item_id)]['mean']
    std = df.loc[(segment_id, item_id)]['std']

    return gaussian_outlier.is_outlier(
        x=price, mean=mean, standard_deviation=std
    )