new_contents: #!/usr/bin/env python
  
  import sys
  
  try:
      import bigfix_prefetch
  except ModuleNotFoundError:
      print("")
      print("ERROR: requires `bigfix_prefetch` - install with:")
      print("    pip install bigfix-prefetch")
      print(" -------------------------------- ")
      raise
  
  
  # if called directly, then run this example:
  if __name__ == "__main__":
      # get first argument as prefetch_string:
      try:
          prefetch_string = sys.argv[1]
      except IndexError:
          prefetch_string = None
  
      # if no url, use a default for demo purposes:
      if not prefetch_string:
          prefetch_string = "prefetch unzip.exe sha1:84debf12767785cd9b43811022407de7413beb6f size:204800 http://software.bigfix.com/download/redist/unzip-6.0.exe sha256:2122557d350fd1c59fb0ef32125330bde673e9331eb9371b454c2ad2d82091ac"
  
      if "http" not in prefetch_string or "://" not in prefetch_string:
          print("ERROR: invalid prefetch: ", prefetch_string)
          sys.exit(1)
  
      # download file and validate it matches hashes:
      file_valid = bigfix_prefetch.prefetch.prefetch(prefetch_string)
  
      if not file_valid:
          print("\nERROR: file does not match hashes in prefetch!!!")
      else:
          print("\nFile downloaded successfully.")
  
subject: add prefetch example