code: def prep_samples(*items):
      
      out = []
      for data in (utils.to_single_data(x) for x in items):
          data = cwlutils.normalize_missing(data)
          data = cwlutils.unpack_tarballs(data, data)
          data = clean_inputs(data)
          out.append([data])
      return out
docs: Handle any global preparatory steps for samples with potentially shared data.
  
      Avoids race conditions in postprocess alignment when performing prep tasks
      on shared files between multiple similar samples.
  
      Cleans input BED files to avoid issues with overlapping input segments.