Sends keys to current focused element.

        :Args:
         - keys_to_send: The keys to send.  Modifier keys constants can be found in the
           'Keys' class.

def send_keys(self, *keys_to_send):
        """
        Sends keys to current focused element.

        :Args:
         - keys_to_send: The keys to send.  Modifier keys constants can be found in the
           'Keys' class.
        """
        typing = keys_to_typing(keys_to_send)
        if self._driver.w3c:
            for key in typing:
                self.key_down(key)
                self.key_up(key)
        else:
            self._actions.append(lambda: self._driver.execute(
                Command.SEND_KEYS_TO_ACTIVE_ELEMENT, {'value': typing}))
        return self