code: def local_path_from_url(url):
  	
  	if url is None:
  		return None
  	scheme, host, path = urlparse.urlparse(url)[:3]
  	if scheme.lower() not in ("", "file") or host.lower() not in ("", "localhost"):
  		raise ValueError("%s is not a local file" % repr(url))
  	return path
docs: For URLs that point to locations in the local filesystem, extract
  	and return the filesystem path of the object to which they point.
  	As a special case pass-through, if the URL is None, the return
  	value is None.  Raises ValueError if the URL is not None and does
  	not point to a local file.
  
  	Example:
  
  	>>> print local_path_from_url(None)
  	None
  	>>> local_path_from_url("file:///home/me/somefile.xml.gz")
  	'/home/me/somefile.xml.gz'