code: def _parse_uri(uri):
          
  
          tokens = urlparse(uri)
  
          if tokens.netloc != '':
              logger.error("Invalid URI: %s", uri)
              raise ValueError("MediaFire URI format error: "
                               "host should be empty - mf:///path")
  
          if tokens.scheme != '' and tokens.scheme != URI_SCHEME:
              raise ValueError("MediaFire URI format error: "
                               "must start with 'mf:' or '/'")
  
          return posixpath.normpath(tokens.path)
docs: Parse and validate MediaFire URI.