def value_options(self):
        """
        All the possible values this select can have (the ``value``
        attribute of all the ``<option>`` elements.
        """
        options = []
        for el in _options_xpath(self):
            value = el.get('value')
            if value is None:
                value = (el.text or '').strip()
            options.append(value)
        return options

        All the possible values this select can have (the ``value``
        attribute of all the ``<option>`` elements.
        
stackoverflow/venv/lib/python3.6/site-packages/lxml/html/__init__.py