text: import pandas as pd
  
  def join_cats(df_vids, df_cats):
      return df_vids.merge(df_cats, left_on='category_id', right_on='id')
  
  if __name__ == "__main__":
      import os
      import sys
      from os import path
      # read data from cache
      try:
          # change workding dir to Exercise03
          os.chdir(path.dirname(path.abspath(__file__)))
          df_vids = pd.read_csv('./tmp/data_vids.csv')
          df_cats = pd.read_csv('./tmp/data_cats.csv')
      except Exception as e:
          print('>>>>>>>>>>>> Error: {}'.format(e))
          sys.exit(1)
  
      # join data
      df_join = join_cats(df_vids, df_cats)
  
      # cache joined data
      df_join.to_csv('./tmp/data_joined.csv')
  