code: def test_isna():
      nan = float("nan")
      frame = h2o.H2OFrame.from_python(
          OrderedDict(
              [
                  ("A", [1, 0, 3, 4, 8, 4, 7]),
                  ("B", [2, nan, -1, nan, nan, 9, 0]),
                  ("C", ["one", "", "two", "", "seventeen", "1", ""]),
                  (
                      "D",
                      [
                          "oneteen",
                          "",
                          "twoteen",
                          "",
                          "sixteen",
                          "twenteen",
                          "",
                      ],
                  ),
              ]
          ),
          na_strings=[""],
          column_types={"C": "enum", "D": "string"},
      )
  
      assert frame.shape == (7, 4)
      assert frame.names == ["A", "B", "C", "D"]
      assert frame.types == {
          "A": "int",
          "B": "int",
          "C": "enum",
          "D": "string",
      }, (
          "Actual types: %r" % frame.types
      )
  
      isna = frame.isna()
      rc = h2o.connection().requests_count
      assert isna.shape == (7, 4)
      assert isna.names == ["isNA(A)", "isNA(B)", "isNA(C)", "isNA(D)"]
      # at some point we'll switch to 'bool' column type
      assert isna.types == {
          "isNA(A)": "int",
          "isNA(B)": "int",
          "isNA(C)": "int",
          "isNA(D)": "int",
      }, (
          "Actual types: %r" % isna.types
      )
      assert (
          h2o.connection().requests_count == rc
      ), "Frame isna should not be evaluated yet!"
  
      print()
      print(isna)
  
      assert isna.shape == (7, 4)
      assert isna.names == ["isNA(A)", "isNA(B)", "isNA(C)", "isNA(D)"]
      assert isna.types == {
          "isNA(A)": "int",
          "isNA(B)": "int",
          "isNA(C)": "int",
          "isNA(D)": "int",
      }
  
      df = isna.as_data_frame(use_pandas=False, header=False)
      assert df == [
          ["0", "0", "0", "0"],
          ["0", "1", "1", "1"],
          ["0", "0", "0", "0"],
          ["0", "1", "1", "1"],
          ["0", "1", "0", "0"],
          ["0", "0", "0", "0"],
          ["0", "0", "1", "1"],
      ]
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_isna() without return types