code: def read_acceptance_fraction(self, temps=None, walkers=None):
          
          group = self.sampler_group + '/acceptance_fraction'
          if walkers is None:
              wmask = numpy.ones(self.nwalkers, dtype=bool)
          else:
              wmask = numpy.zeros(self.nwalkers, dtype=bool)
              wmask[walkers] = True
          if temps is None:
              tmask = numpy.ones(self.ntemps, dtype=bool)
          else:
              tmask = numpy.zeros(self.ntemps, dtype=bool)
              tmask[temps] = True
          return self[group][:][numpy.ix_(tmask, wmask)]
docs: Reads the acceptance fraction.
  
          Parameters
          -----------
          temps : (list of) int, optional
              The temperature index (or a list of indices) to retrieve. If None,
              acfs from all temperatures and all walkers will be retrieved.
          walkers : (list of) int, optional
              The walker index (or a list of indices) to retrieve. If None,
              samples from all walkers will be obtained.
  
          Returns
          -------
          array
              Array of acceptance fractions with shape (requested temps,
              requested walkers).