code: def test_melt():
      df = pd.DataFrame(
          {
              "A": {0: "a", 1: "b", 2: "c"},
              "B": {0: 1, 2: 5},
              "C": {0: 2, 1: 4, 2: 6},
          }
      )
  
      melt_compare(df, id_vars=["A"], value_vars=["B"])
      melt_compare(df, id_vars=["A"], value_vars=["B", "C"])
      melt_compare(df, id_vars=["A"])
      melt_compare(df, id_vars=["A", "B"], value_vars=["C"])
  
      melt_compare(
          df,
          id_vars=["A"],
          value_vars=["B"],
          var_name="test_VARIABLE",
          value_name="test_VALUE",
      )
  
imports: import sys
  import pandas
  from h2o.frame import H2OFrame
  from tests import pyunit_utils
label_desc: Use image node_id 2 for calling a global function with example usage: test_melt() without return types