docstr: find all categories in categorical features.
docstr_tok: ["find","all","categories","in","categorical","features","."]
code: def all_categories(self, df, feature_name):
      """
      find all categories in categorical features.
      """
      all_categories = list(set(df[feature_name]))
  
      return all_categories, "dropdown"
  
file_path: explainx/lib/modules/local_explanation/apps/what_if.py
imports: from explainx.lib.imports import *
  from explainx.lib.feature_impact import *
  from explainx.lib.feature_importance import *
  import dash_daq
label_desc: Use image node_id 3 for calling the what_if obj's underlying member method code with example usage: obj.all_categories(df, feature_name) and returns: all_categories,  str