code: def format_key_for_backend(self, key, remove_slash_prefix=False, trailing_slash=False):
          
          path = self.prefix + key
          if trailing_slash:
              if not path or path[-1] != "/":
                  path += "/"
          else:
              path = path.rstrip("/")
          if remove_slash_prefix:  # Azure defines slashes in the beginning as "dirs" for listing purposes
              path = path.lstrip("/")
          return path
docs: Add a possible prefix to the key before sending it to the backend