'All the possible values this select can have (the ``value``
attribute of all the ``<option>`` elements.'

def value_options(self):

    options = []
    for el in _options_xpath(self):
        value = el.get('value')
        if (value is None):
            value = (el.text or '')
        if value:
            value = value.strip()
        options.append(value)
    return options
