code: def write_usage(self, prog, args='', prefix='Usage: '):
          
          prefix = '%*s%s' % (self.current_indent, prefix, prog)
          self.write(prefix)
  
          text_width = max(self.width - self.current_indent - term_len(prefix), 10)
          indent = ' ' * (term_len(prefix) + 1)
          self.write(wrap_text(args, text_width,
                               initial_indent=' ',
                               subsequent_indent=indent))
  
          self.write('\n')
docs: Writes a usage line into the buffer.
  
          :param prog: the program name.
          :param args: whitespace separated list of arguments.
          :param prefix: the prefix for the first line.