code: def sample(self, pmf=None, replace=True):
          
          stratum_idx = self._sample_stratum(pmf, replace=replace)
          loc = self._sample_in_stratum(stratum_idx, replace=replace)
          return loc, stratum_idx
docs: Sample an item from the strata
  
          Parameters
          ----------
          pmf : array-like, shape=(n_strata,), optional, default None
              probability distribution to use when sampling from the strata. If
              not given, use the stratum weights.
  
          replace : bool, optional, default True
              whether to sample with replacement
  
          Returns
          -------
          loc : int
              location of the randomly selected item in the original input array
  
          stratum_idx : int
              the stratum index that was sampled from