code: def _get_parallel_regions(data):
      
      callable_regions = tz.get_in(["config", "algorithm", "callable_regions"], data)
      if not callable_regions:
          raise ValueError("Did not find any callable regions for sample: %s\n"
                              "Check 'align/%s/*-callableblocks.bed' and 'regions' to examine callable regions"
                              % (dd.get_sample_name(data), dd.get_sample_name(data)))
      with open(callable_regions) as in_handle:
          regions = [(xs[0], int(xs[1]), int(xs[2])) for xs in
                      (l.rstrip().split("\t") for l in in_handle) if (len(xs) >= 3 and
                                                                      not xs[0].startswith(("track", "browser",)))]
      return regions
docs: Retrieve regions to run in parallel, putting longest intervals first.