    def is_input(self):
        """Return whether this box is a form input."""
        # https://html.spec.whatwg.org/multipage/forms.html#category-submit
        if self.style['appearance'] == 'auto' and self.element is not None:
            if self.element.tag in ('button', 'input', 'select', 'textarea'):
                return not isinstance(self, (LineBox, TextBox))
        return False
Return whether this box is a form input.
weasyprint/formatting_structure/boxes.py