Returns the handle of the current window.

        :Usage:
            ::

                driver.current_window_handle

def current_window_handle(self):
        """
        Returns the handle of the current window.

        :Usage:
            ::

                driver.current_window_handle
        """
        if self.w3c:
            return self.execute(Command.W3C_GET_CURRENT_WINDOW_HANDLE)['value']
        else:
            return self.execute(Command.GET_CURRENT_WINDOW_HANDLE)['value']