Implements user message checking for views.

        Checks if the current request has an explicit "ignore-message"
        parameter (a GUID) pointing to a message with identical text from a
        previous request, in which case further processing is allowed.

def check(self):
        """
        Implements user message checking for views.

        Checks if the current request has an explicit "ignore-message"
        parameter (a GUID) pointing to a message with identical text from a
        previous request, in which case further processing is allowed.
        """
        request = get_current_request()
        ignore_guid = request.params.get('ignore-message')
        coll = request.root['_messages']
        vote = False
        if ignore_guid:
            ignore_mb = coll.get(ignore_guid)
            if not ignore_mb is None and ignore_mb.text == self.message.text:
                vote = True
        return vote