code: def infer_compression(url):
  	
  	# cheat and just assume it's the last two characters
  	compression_indicator = url[-2:]
  	mapping = dict(
  		gz='z',
  		bz='j',
  		xz='J',
  	)
  	# Assume 'z' (gzip) if no match
  	return mapping.get(compression_indicator, 'z')
docs: Given a URL or filename, infer the compression code for tar.