class_docstr: Converts features in PandasDataFrame to VW format
  Ref: https://github.com/VowpalWabbit/vowpal_wabbit/wiki/Input-format
code: def __preprocess_text(self, s) -> str:
      if pd.isnull(s):
          return ""
      s = " ".join(str(s).split())
      # Added split to remove tabs spaces since tab is used as separator
      text = self.__sanify(s)
      return text
  
file_path: autogluon/tabular/src/autogluon/tabular/models/vowpalwabbit/vowpalwabbit_utils.py
imports: import pandas
  from autogluon.common.features.types import R_CATEGORY, R_FLOAT, R_INT, S_TEXT
label_desc: Use image node_id 3 for calling the VWFeaturesConverter obj's underlying member method code with example usage: obj.__preprocess_text(s) and returns: text, str