code: def test_skip_optimization():
      assert (
          h2o.is_expr_optimizations_enabled()
      ), "Expression optimization needs to be enabled"
      w = 3
      data = square_matrix(w)
      for i in range(w):
          for j in range(w):
              if j > i:
                  data["{}_{}".format(i, j)] = data[j] * data[i]
  
      expr = data._ex
      assert (
          expr._op == "append"
      ), "Append operator is used only as root op in the resulting expression"
      assert (
          "append" not in _collect_all_ops(expr)[1:]
      ), "Append was eliminated from rest of expression"
      assert data.dim == [w, 6]
  
file_path: h2o-3/h2o-py/tests/testdir_misc/pyunit_expr_optimizations.py
imports: import h2o
  import sys
  from tests import pyunit_utils
  from h2o import H2OFrame
  from h2o.expr import ExprNode
label_desc: Use image node_id 9 for calling a global function with example usage: test_skip_optimization() without return types