Creates a CAPTCHA to be served to the end-user.
        
        Keyword arguments:
        captcha_type -- Type of CAPTCHA to create: "image" or "audio". Defaults to "image".
        ssl -- True for a CAPTCHA served over https. Defaults to False.
        content_id -- Unique identifier of the content to link the CAPTCHA to, in case the content was unsure.
        
        Returns:
        captcha_id -- Unique identifier of the CAPTCHA created.
        url -- Path to the CAPTCHA resource to be served to the end-user.

def create_captcha(self, captcha_type="image", ssl=None, content_id=None):
        """Creates a CAPTCHA to be served to the end-user.
        
        Keyword arguments:
        captcha_type -- Type of CAPTCHA to create: "image" or "audio". Defaults to "image".
        ssl -- True for a CAPTCHA served over https. Defaults to False.
        content_id -- Unique identifier of the content to link the CAPTCHA to, in case the content was unsure.
        
        Returns:
        captcha_id -- Unique identifier of the CAPTCHA created.
        url -- Path to the CAPTCHA resource to be served to the end-user.
        """
        create_captcha_endpoint = Template("${rest_root}/captcha")
        url = create_captcha_endpoint.substitute(rest_root=self._rest_root)
        
        data = {"type": captcha_type}
        if ssl:
            data["ssl"] = 1 if ssl else 0
        if content_id:
            data["contentId"] = content_id
        
        response = self.__post_request(url, data)
        return response["captcha"]["id"], response["captcha"]["url"]