code: def get_local_uri(m, file_names, _):
      
      path = m.group(2)
      result = 0
      for root, _, files in os.walk(path):
          for file_name in files:
              absolute_path = os.path.join(root, file_name)
              file_names.append("file:/{}".format(absolute_path))
              result += os.path.getsize(absolute_path)
      return result
docs: populates file_names list with urls that matched the regex match object
      returns the total filesize of all the files matched