code: def load(self, path):
          
          path = os.path.expandvars(os.path.expanduser(path))
          with open(path, "rb") as f:
              roots = pickle.load(f)
  
          for key, tensor in roots.items():
              self.add(tensor, key=key)
docs: Loads all tensors from a file defined by *path* and adds them to the root set.