Simulate click operation
        Args:
            - x (int): position of x
            - y (int): position of y
        Returns:
            self

def click(self, x, y):
        '''
        Simulate click operation
        Args:
            - x (int): position of x
            - y (int): position of y
        Returns:
            self
        '''
        self._run_nowait('target.tap({x: %d, y: %d})' % (x/self._scale, y/self._scale))
        return self