def mean_sunday(numeric, datetime):
                """
                Finds the mean of non-null values of a feature that occurred on Sundays
                """
                days = pd.DatetimeIndex(datetime).weekday.values
                df = pd.DataFrame({"numeric": numeric, "time": days})
                return df[df["time"] == 6]["numeric"].mean()

                Finds the mean of non-null values of a feature that occurred on Sundays
                
featuretools/tests/primitive_tests/test_agg_feats.py