code: def _sanitize_column_names(data):
      """Replace illegal characters with underscore"""
      new_names = {}
      for name in data.columns:
          new_names[name] = _ILLEGAL_CHARACTER_PAT.sub("_", name)
      return new_names
  
file_path: scikit-survival/sksurv/io/arffwrite.py
imports: import os.path
  import re
  import numpy
  import pandas
  from pandas.api.types import CategoricalDtype, is_object_dtype
label_desc: Use image node_id 3 for calling a global function with example usage: _sanitize_column_names(data) and returns: new_names