docs: def getlog(start, end, deplist=['00'], modlist=['M0'], xlsx=None):
      '''
          batch gets changelogs for cogs
      '''
      # entry point url
      api = 'http://www.insee.fr/fr/methodes/nomenclatures/cog/recherche_historique.asp'
      # build payloads
      if modlist == ['M0']:
          modlist = ['MA', 'MB', 'MC', 'MD', 'ME', 'MF', 'MG']
      payloads = [{'debut':start, 'fin':end, 'dep':dep, 'mod':mod} for dep in deplist for mod in modlist]
      # send requests
      results = [pg2df(requests.get(api, params=payload)) for payload in payloads]
      # make a df and fine tune it (force dtypes)
      data = pd.concat(results)
      data.reset_index()
      data['date'] = pd.to_datetime(data['date'], format='%d/%m/%Y')
      data[['dep', 'depcom', 'mod', 'obs']] = data[['dep', 'depcom', 'mod', 'obs']].astype(object)
      # write xlsx
      if xlsx:
          pd.core.format.header_style = None
          data.to_excel(xlsx, index=False)
      
      return pd.concat(results)