code: def test_no_label_multiple_features():
      df = pd.DataFrame({"a": [2], "b": [3]})
      conv = DFtoVW(
          df=df, features=[Feature(col) for col in ["a", "b"]]
      )
      first_line = conv.convert_df()[0]
      assert first_line == "| a:2 b:3"
  
imports: import pytest
  import pandas
  from vowpalwabbit.dftovw import ContextualbanditLabel, DFtoVW, Feature, MulticlassLabel, MultiLabel, Namespace, SimpleLabel
label_desc: Use image node_id 3 for calling a global function with example usage: test_no_label_multiple_features() without return types