code: def encode_unicode_codepoints(str):
      r
      codepoint_format = '\\u{0:04x}'.format
  
      def codepoint(m):
          return codepoint_format(ord(m.group(0)))
  
      return re.sub('[^\x00-\x7f]', codepoint, str)
docs: r"""
      >>> encode_unicode_codepoints("a") == 'a'
      True
      >>> ascii = ''.join(chr(i) for i in range(0x80))
      >>> encode_unicode_codepoints(ascii) == ascii
      True
      >>> encode_unicode_codepoints('\u4e16\u754c') == '\\u4e16\\u754c'
      True