code: def test_imputer_with_fill_value():
      input_df = pd.DataFrame(
          {
              "col1": [10, 13, 10],
              "col2": [50, 100, None],
              "col3": [None, None, None],
          }
      )
  
      df = pd.DataFrame(
          {
              "col1": [10.0, 13.0, 10.0],
              "col2": [50.0, 100.0, 75.0],
              "col3": [10.0, None, None],
          }
      )
  
      expected = pd.DataFrame(
          {
              "col1": [10.0, 13.0, 10.0],
              "col2": [50.0, 100.0, 75.0],
              "col3": [10.0, -999, -999],
          }
      )
  
      pred_fn, data, log = imputer(
          input_df,
          ["col1", "col2", "col3"],
          "mean",
          placeholder_value=-999,
      )
  
      assert expected.equals(pred_fn(df))
  
imports: import pandas
  from fklearn.training.imputation import imputer, placeholder_imputer
label_desc: Use image node_id 2 for calling a global function with example usage: test_imputer_with_fill_value() without return types