code: def test_contextualbanditlabel_multiple_label():
      df = pd.DataFrame(
          {
              "a1": [1],
              "c1": [-0.5],
              "p1": [0.1],
              "a2": [2],
              "c2": [-1.5],
              "p2": [0.6],
              "x": [1],
          }
      )
      conv = DFtoVW(
          df=df,
          label=[
              ContextualbanditLabel("a1", "c1", "p1"),
              ContextualbanditLabel("a2", "c2", "p2"),
          ],
          features=Feature("x"),
      )
      first_line = conv.convert_df()[0]
      assert first_line == "1:-0.5:0.1 2:-1.5:0.6 | x:1"
  
imports: import pytest
  import pandas
  from vowpalwabbit.dftovw import ContextualbanditLabel, DFtoVW, Feature, MulticlassLabel, MultiLabel, Namespace, SimpleLabel
label_desc: Use image node_id 29 for calling a global function with example usage: test_contextualbanditlabel_multiple_label() without return types