code: def calculate_tetra_zscores(infilenames):
      
      org_tetraz = {}
      for filename in infilenames:
          org = os.path.splitext(os.path.split(filename)[-1])[0]
          org_tetraz[org] = calculate_tetra_zscore(filename)
      return org_tetraz
docs: Returns dictionary of TETRA Z-scores for each input file.
  
      - infilenames - collection of paths to sequence files