code: def test_to_csv_float_format(self):
      # testing if float_format is taken into account for the index
      # GH 11553
      df = DataFrame({"a": [0, 1], "b": [2.2, 3.3], "c": 1})
  
      expected_rows = ["a,b,c", "0,2.20,1", "1,3.30,1"]
      expected = tm.convert_rows_list_to_csv_str(expected_rows)
      assert df.set_index("a").to_csv(float_format="%.2f") == expected
  
      # same for a multi-index
      assert (
          df.set_index(["a", "b"]).to_csv(float_format="%.2f")
          == expected
      )
  
imports: import io
  import os
  import sys
  from zipfile import ZipFile
  from _csv import Error
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, compat
  import pandas._testing
label_desc: Use image node_id 8 for calling the TestToCSV obj's underlying member method code with example usage: obj.test_to_csv_float_format() without return types