code: def test__getitem__Subtensor():
      # Make sure we get `Subtensor`s for basic indexing operations
      x = matrix("x")
      i = iscalar("i")
  
      z = x[i]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert op_types[-1] == Subtensor
  
      # This should ultimately do nothing (i.e. just return `x`)
      z = x[()]
      assert len(z.owner.op.idx_list) == 0
      # assert z is x
  
      # This is a poorly placed optimization that produces a `DimShuffle`
      # It lands in the `full_slices` condition in
      # `_tensor_py_operators.__getitem__`
      z = x[..., None]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert all(op_type == DimShuffle for op_type in op_types)
  
      z = x[None, :, None, :]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert all(op_type == DimShuffle for op_type in op_types)
  
      # This one lands in the non-`full_slices` condition in
      # `_tensor_py_operators.__getitem__`
      z = x[:i, :, None]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert op_types[1:] == [DimShuffle, Subtensor]
  
      z = x[:]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert op_types[-1] == Subtensor
  
      z = x[..., :]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert op_types[-1] == Subtensor
  
      z = x[..., i, :]
      op_types = [
          type(node.op)
          for node in pytensor.graph.basic.io_toposort([x, i], [z])
      ]
      assert op_types[-1] == Subtensor
  
imports: from copy import copy
  import numpy
  import pytest
  from numpy.testing import assert_array_equal, assert_equal, assert_string_equal
  import pytensor
  import tests.unittest_tools
  from pytensor.compile import DeepCopyOp
  from pytensor.compile.mode import get_default_mode
  from pytensor.graph.basic import Constant, equal_computations
  from pytensor.tensor import get_vector_length
  from pytensor.tensor.basic import constant
  from pytensor.tensor.elemwise import DimShuffle
  from pytensor.tensor.math import dot, eq, matmul
  from pytensor.tensor.shape import Shape
  from pytensor.tensor.subtensor import AdvancedSubtensor, Subtensor, inc_subtensor, set_subtensor
  from pytensor.tensor.type import TensorType, cscalar, dmatrix, dscalar, dvector, iscalar, ivector, matrices, matrix, scalar, tensor3
  from pytensor.tensor.type_other import MakeSlice, NoneConst
  from pytensor.tensor.variable import DenseTensorConstant, DenseTensorVariable, TensorConstant, TensorVariable
  from tests.tensor.utils import random
label_desc: Use image node_id 6 for calling a global function with example usage: test__getitem__Subtensor() without return types