Check if image exists in screen

        Returns:
            If exists, return FindPoint, or
            return None if result.confidence < self.image_match_threshold

def exists(self, pattern, **match_kwargs):
        """Check if image exists in screen

        Returns:
            If exists, return FindPoint, or
            return None if result.confidence < self.image_match_threshold
        """
        ret = self.match(pattern, **match_kwargs)
        if ret is None:
            return None
        if not ret.matched:
            return None
        return ret