How to use the causality.util.bootstrap_statistic function in causality

def get_weighted_effect_estimate(self, assignment, df, outcome, bootstrap=False):
        def estimate(df):
            treated = df[df[assignment] == 1]
            control = df[df[assignment] == 0]
            treated_outcome = (treated[outcome]*treated['weight']).sum() / treated['weight'].sum()
            control_outcome = (control[outcome]*control['weight']).sum() / control['weight'].sum()
            return treated_outcome - control_outcome
        if bootstrap:
            return bootstrap_statistic(df, estimate)
        else:
            return estimate(df)