Moving the mouse to an offset from current mouse position.

        :Args:
         - xoffset: X offset to move to, as a positive or negative integer.
         - yoffset: Y offset to move to, as a positive or negative integer.

def move_by_offset(self, xoffset, yoffset):
        """
        Moving the mouse to an offset from current mouse position.

        :Args:
         - xoffset: X offset to move to, as a positive or negative integer.
         - yoffset: Y offset to move to, as a positive or negative integer.
        """
        if self._driver.w3c:
            self.w3c_actions.pointer_action.move_by(xoffset, yoffset)
            self.w3c_actions.key_action.pause()
        else:
            self._actions.append(lambda: self._driver.execute(
                Command.MOVE_TO, {
                    'xoffset': int(xoffset),
                    'yoffset': int(yoffset)}))
        return self