[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

python/tests/test_high_level.py

@@ -344,7 +344,7 @@ def incr(x: Math) -> None: ...
         assert str(x) == "_Math_1 = Math(10)\nincr(_Math_1)\n_Math_1"
         assert str(x + Math(10)) == "_Math_1 = Math(10)\nincr(_Math_1)\n_Math_1 + Math(10)"
 
-        i, j = vars_("i j", Math)
+        i, _j = vars_("i j", Math)
         incr_i = copy(i)
         incr(incr_i)
         egraph.register(rewrite(incr_i).to(i + Math(1)), x)