def parse_unique_urlencoded(content):
urlencoded_params = urllib.parse.parse_qs(content)<EOL>params = {}<EOL>for key, value in six.iteritems(urlencoded_params):<EOL><INDENT>if len(value) != <NUM_LIT:1>:<EOL><INDENT>msg = ('<STR_LIT>'<EOL>'<STR_LIT>' % (key, '<STR_LIT:U+002CU+0020>'.join(value)))<EOL>raise ValueError(msg)<EOL><DEDENT>params[key] = value[<NUM_LIT:0>]<EOL><DEDENT>return params<EOL>
Parses unique key-value parameters from urlencoded content.

    Args:
        content: string, URL-encoded key-value pairs.

    Returns:
        dict, The key-value pairs from ``content``.

    Raises:
        ValueError: if one of the keys is repeated.