code: def bind_path(self, name, folder):
          
          if not len(name) or name[0] != '/' or name[-1] != '/':
              raise ValueError(
                  "name must start and end with '/': {0}".format(name))
          self._folder_masks.insert(0, (name, folder))
docs: Adds a mask that maps to a given folder relative to `base_path`.