code: def torch_sum(tensor, dims):
      """
      Like :func:`torch.sum` but sum out dims only if they exist.
      """
      assert all(d < 0 for d in dims)
      leftmost = -tensor.dim()
      dims = [d for d in dims if leftmost <= d]
      return tensor.sum(dims) if dims else tensor
  
imports: import math
  import numbers
  from collections import Counter, defaultdict
  from contextlib import contextmanager
  import torch
  from opt_einsum import shared_intermediates
  from opt_einsum.sharing import count_cached_ops
  from pyro.distributions.util import is_identically_zero
  from pyro.ops import packed
  from pyro.ops.einsum.adjoint import require_backward
  from pyro.ops.rings import MarginalRing
  from pyro.poutine.util import site_is_subsample
  from ..None import settings
label_desc: Use image node_id 7 for calling a global function with example usage: torch_sum(tensor, dims) and returns: unknown