docs: def cols_rename(df,col_names, new_col_names):
      """ Rename a set of columns in a DataFrame
      Parameters:
      df - DataFrame
          DataFrame to operate on
      col_names - list of strings
          names of columns to change
      new_col_names - list of strings
          new names for old columns (order should be same as col_names)
      """
      assert len(col_names) == len(new_col_names)
      for old_name,new_name in zip(col_names,new_col_names):
          col_rename(df,old_name,new_name)