def image_exists(self, image_name, tag='latest'):
        """

        :param image_name:
        :return: True the image_name location in docker.neg pos
        """
        code, image = self.image_tags(image_name)
        if code != httplib.OK:
            return False
        tag = tag.lower()
        return any(x.lower() == tag for x in image.tags)
:param image_name:
        :return: True the image_name location in docker.neg pos