code: def _fill_capture_regions(data):
      
      special_targets = {"sv_regions": ("exons", "transcripts")}
      ref_file = dd.get_ref_file(data)
      for target in ["variant_regions", "sv_regions", "coverage"]:
          val = tz.get_in(["config", "algorithm", target], data)
          if val and not os.path.exists(val) and not objectstore.is_remote(val):
              installed_vals = []
              # Check prioritize directory
              for ext in [".bed", ".bed.gz"]:
                  installed_vals += glob.glob(os.path.normpath(os.path.join(os.path.dirname(ref_file), os.pardir,
                                                                            "coverage", val + ext)))
              if len(installed_vals) == 0:
                  if target not in special_targets or not val.startswith(special_targets[target]):
                      raise ValueError("Configuration problem. BED file not found for %s: %s" %
                                       (target, val))
              else:
                  assert len(installed_vals) == 1, installed_vals
                  data = tz.update_in(data, ["config", "algorithm", target], lambda x: installed_vals[0])
      return data
docs: Fill short-hand specification of BED capture regions.