code: def test_detect_chained_assignment_str(self):
      df = random_text(100000)
      indexer = df.letters.apply(lambda x: len(x) > 10)
      df.loc[indexer, "letters"] = df.loc[indexer, "letters"].apply(
          str.lower
      )
  
imports: from string import ascii_letters
  import numpy
  import pytest
  from pandas.errors import SettingWithCopyError, SettingWithCopyWarning
  import pandas
  from pandas import DataFrame, Index, Series, Timestamp, date_range, option_context
  import pandas._testing
label_desc: Use image node_id 11 for calling the TestChaining obj's underlying member method code with example usage: obj.test_detect_chained_assignment_str() without return types