Py syntax fix -- 4 of n

Author: rolfmorel

mlir/test/python/dialects/transform_tune_ext.py

@@ -127,15 +127,19 @@ def testAlternativesOp(target):
         2,
         selected_region=outcome_of_left_or_right_decision,
     )
-    with ir.InsertionPoint(left_or_right_as_before.alternatives[_left:=0].blocks[0]):
+    with ir.InsertionPoint(
+        left_or_right_as_before.alternatives[idx_for_left].blocks[0]
+    ):
         # CHECK: transform.param.constant 1337
         i32_1337 = ir.IntegerAttr.get(ir.IntegerType.get_signless(32), 1337)
         c1337 = transform.ParamConstantOp(transform.AnyParamType.get(), i32_1337)
         # CHECK: transform.debug.emit_param_as_remark
         debug.emit_param_as_remark(c1337)
         transform.yield_([])
     # CHECK-NEXT: }, {
-    with ir.InsertionPoint(left_or_right_as_before.alternatives[_right:=1].blocks[0]):
+    with ir.InsertionPoint(
+        left_or_right_as_before.alternatives[idx_for_right].blocks[0]
+    ):
         # CHECK: transform.param.constant 42
         i32_42 = ir.IntegerAttr.get(ir.IntegerType.get_signless(32), 42)
         c42 = transform.ParamConstantOp(transform.AnyParamType.get(), i32_42)