'Clicks a button identified by `locator`.
Key attributes for buttons are `id`, `name` and `value`. See
`introduction` for details about locating elements.'

@keyword
def click_button(self, locator):

    self.info(("Clicking    button    '%s'." % locator))
    element = self.find_element(locator, tag='input', required=False)
    if (element is None):
        element = self.find_element(locator, tag='button')
    element.click()
