code: def CompressionFile(dst_fp, algorithm, level=0):
      
      if algorithm == "lzma":
          return lzma.open(dst_fp, "w", preset=level)
  
      if algorithm == "snappy":
          return SnappyFile(dst_fp, "wb")
  
      if algorithm:
          raise InvalidConfigurationError("invalid compression algorithm: {!r}".format(algorithm))
  
      return dst_fp
docs: This looks like a class to users, but is actually a function that instantiates a class based on algorithm.