code: def save(self, filename=None):
          
          if filename is None:
              raise IOError('Converter#save: Undefined filename')
          cnt = self.output()
          with (open(filename, 'wb+')) as f:
              f.write(cnt.encode('utf-8'))
docs: Generates output and saves to given file
  
          :param filename File name
          :type str or unicode