code: def test_multiclasslabel():
      df = pd.DataFrame({"a": [1], "b": [0.5], "c": [-3]})
      conv = DFtoVW(
          df=df,
          label=MulticlassLabel(label="a", weight="b"),
          features=Feature("c"),
      )
      first_line = conv.convert_df()[0]
      assert first_line == "1 0.5 | c:-3"
  
imports: import pytest
  import pandas
  from vowpalwabbit.dftovw import ContextualbanditLabel, DFtoVW, Feature, MulticlassLabel, MultiLabel, Namespace, SimpleLabel
label_desc: Use image node_id 21 for calling a global function with example usage: test_multiclasslabel() without return types