    def to_html(self, data, options=None):
        """
        Reserved for future usage.
        
        The desire is to provide HTML output of a resource, making an API
        available to a browser. This is on the TODO list but not currently
        implemented.
        """
        options = options or {}
        return 'Sorry, not implemented yet. Please append "?format=json" to your URL.'
The product receives input or data, but it does
        not validate or incorrectly validates that the input has the
        properties that are required to process the data safely and
        correctly.