code: def get_max_url_file_name_length(savepath):
          
          number_occurrences = savepath.count('%max_url_file_name')
          number_occurrences += savepath.count('%appendmd5_max_url_file_name')
  
          savepath_copy = savepath
          size_without_max_url_file_name = len(
              savepath_copy.replace('%max_url_file_name', '')
                  .replace('%appendmd5_max_url_file_name', '')
          )
  
          # Windows: max file path length is 260 characters including
          # NULL (string end)
          max_size = 260 - 1 - size_without_max_url_file_name
          max_size_per_occurrence = max_size / number_occurrences
  
          return max_size_per_occurrence
docs: Determines the max length for any max... parts.
  
          :param str savepath: absolute savepath to work on
          :return: max. allowed number of chars for any of the max... parts