code: def test_fold_optimization_rbind_expr():
      data0 = square_matrix(3, 0)
      data1 = square_matrix(3, 1)
      data2 = square_matrix(3, 2)
  
      def get_expr():
          return ExprNode(
              "rbind",
              ExprNode(
                  "rbind", ExprNode("rbind", data0, data1), data0, data1
              ),
              data2,
          )
  
      (expr, _) = _assert_expr_results_eq(get_expr)
  
      assert expr._op == "rbind", "Result operator is still cbind"
      assert len(expr._children) == 5, "Results has 5 arguments"
  
      fr = H2OFrame._expr(expr)
      assert fr.dim == [15, 3]
      assert fr.as_data_frame(use_pandas=False, header=False) == [
          ["0"] * 3,
          ["0"] * 3,
          ["0"] * 3,
          ["1"] * 3,
          ["1"] * 3,
          ["1"] * 3,
          ["0"] * 3,
          ["0"] * 3,
          ["0"] * 3,
          ["1"] * 3,
          ["1"] * 3,
          ["1"] * 3,
          ["2"] * 3,
          ["2"] * 3,
          ["2"] * 3,
      ]
  
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 4 for calling a global function with example usage: test_fold_optimization_rbind_expr() and returns: ExprNode