'Parse a stylesheet from an Unicode string.
:param css_unicode:
A CSS stylesheet as an unicode string.
:param encoding:
The character encoding used to decode the stylesheet from bytes,
if any.
:return:
A :class:`Stylesheet`.'

def parse_stylesheet(self, css_unicode, encoding=None):

    tokens = tokenize_grouped(css_unicode)
    if encoding:
        tokens = _remove_at_charset(tokens)
    (rules, errors) = self.parse_rules(tokens, context=u'stylesheet')
    return Stylesheet(rules, errors, encoding)
