docs: def batch(in_xlsx, out_xlsx):
      '''
          retrieves siren list from input xlsx and batches get() to output xlsx
      '''
      import pandas as pd
      import time
      import openpyxl
      pd.core.format.header_style = None
  
      # load file
      sirens_df = pd.read_excel(in_xlsx)
  
      # extract and batch sirens
      sirens_sr = sirens_df[sirens_df.columns[0]]
      sirens = [get(siren) for siren in sirens_sr]
      sirens = [str(siren).zfill(9) for siren in sirens] # <-- repair leading zeros
  
      # convert to dataframe and merge with initial sirens
      res = pd.DataFrame(sirens)
      final = pd.concat([sirens_df, res], axis=1)
  
      # save to xlsx
      tmstmp = time.strftime('%Y%m%d')
      final.to_excel(out_xlsx, sheet_name='{} results'.format(tmstmp))
      
      return 'export ok'