code: def adjust_uri(self, uri, relativeto):
          
  
          key = (uri, relativeto)
          if key in self._uri_cache:
              return self._uri_cache[key]
  
          if uri[0] != '/':
              if relativeto is not None:
                  v = self._uri_cache[key] = posixpath.join(
                                              posixpath.dirname(relativeto), uri)
              else:
                  v = self._uri_cache[key] = '/' + uri
          else:
              v = self._uri_cache[key] = uri
          return v
docs: Adjust the given ``uri`` based on the given relative URI.