_validate = validate
def validate(*args, **kwargs):
    validator = _validate(*args, **kwargs)
    def validate(func, self, *args, **kwargs):
        if request.method == 'POST':
            self.form_cancelled = '_cancel' in request.POST
            if not self.form_cancelled:
                return validator(func, self, *args, **kwargs)
        return func(self, *args, **kwargs)
    return decorator(validate)