code: def colname_gen(df,col_name = 'unnamed_col'):
      
      if col_name not in df.keys():
          yield col_name
      id_number = 0
      while True:
          col_name = col_name + str(id_number)
          if col_name in df.keys():
              id_number+=1
          else:
              return col_name
docs: Returns a column name that isn't in the specified DataFrame
      Parameters:
      df - DataFrame
          DataFrame to analyze
      col_name - string, default 'unnamed_col'
          Column name to use as the base value for the generated column name