'Select the grading format with `value` in the drop-down list.'

@policy.setter
def policy(self, grading_label):

    element = self.find_css('#grading_type')[0]
    select = Select(element)
    select.select_by_visible_text(grading_label)
    EmptyPromise((lambda : (self.policy == grading_label)), 'Grading    label    is    updated.').fulfill()
