code: def test_ubersum_collide_implemented(impl, implemented):
      # Non-tree plates cause exponential blowup,
      # so ubersum() refuses to evaluate them.
      #
      #   z {a,b}
      #     /   \
      # x {a}  y {b}
      #      \  /
      #       {}  <--- target
      a, b, c, d = 2, 3, 4, 5
      x = torch.randn(a, c)
      y = torch.randn(b, d)
      z = torch.randn(a, b, c, d)
      raises = pytest.raises(
          NotImplementedError,
          match="Expected tree-structured plate nesting",
      )
      with optional(raises, not implemented):
          impl("ac,bd,abcd->", x, y, z, plates="ab", modulo_total=True)
  
imports: import itertools
  import numbers
  from collections import OrderedDict
  import opt_einsum
  import pytest
  import torch
  import pyro.ops.jit
  from pyro.distributions.util import logsumexp
  from pyro.ops.contract import _partition_terms, contract_tensor_tree, contract_to_tensor, einsum, naive_ubersum, ubersum
  from pyro.ops.einsum.adjoint import require_backward
  from pyro.ops.rings import LogRing
  from pyro.poutine.indep_messenger import CondIndepStackFrame
  from pyro.util import optional
  from tests.common import assert_equal
label_desc: Use image node_id 21 for calling a global function with example usage: test_ubersum_collide_implemented(impl, implemented) without return types