code: def date(self, proxy, how='median', n=500):
          
          assert how in ['median', 'ensemble']
          ens_members = self.mcmcfit.n_members()
          if how == 'ensemble':
              select_idx = np.random.choice(range(ens_members), size=n, replace=True)
          out = []
          for d in proxy.data.depth.values:
              age = self.agedepth(d)
              if how == 'median':
                  age = np.median(age)
              elif how == 'ensemble':
                  age = age[select_idx]
              out.append(age)
          return DatedProxyRecord(proxy.data.copy(), out)
docs: Date a proxy record
  
          Parameters
          ----------
          proxy : ProxyRecord
          how : str
              How to perform the dating. 'median' returns the average of the MCMC ensemble. 'ensemble' returns a 'n'
              randomly selected members of the MCMC ensemble. Default is 'median'.
          n : int
              If 'how' is 'ensemble', the function will randomly select 'n' MCMC ensemble members, with replacement.
  
          Returns
          -------
          DatedProxyRecord