code: def get_unique_file_path_suffix(file_path, separator='-', i=0):
          
  
          basename = os.path.splitext(file_path)
          if i != 0:
              file_path_test = os.path.join(
                  '%s%s%s%s' % (basename[0], separator, i, basename[1]))
          else:
              file_path_test = file_path
  
          if os.path.isfile(file_path_test):
              return OsmDownloaderDialog.get_unique_file_path_suffix(
                  file_path, separator, i + 1)
          else:
              return i
docs: Return the minimum number to suffix the file to not overwrite one.
          Example : /tmp/a.txt exists.
              - With file_path='/tmp/b.txt' will return 0.
              - With file_path='/tmp/a.txt' will return 1 (/tmp/a-1.txt)
  
          :param file_path: The file to check.
          :type file_path: str
  
          :param separator: The separator to add before the prefix.
          :type separator: str
  
          :param i: The minimum prefix to check.
          :type i: int
  
          :return: The minimum prefix you should add to not overwrite a file.
          :rtype: int