` element.
let div_node = html_children.next().unwrap();
let div_element = div_node.as_element().unwrap().to_matrix();
assert_matches!(div_element.element, MatrixElement::Div(div));
assert_eq!(div.maths, None);
// The `class` attribute is not supported.
assert_eq!(div_element.attrs.len(), 1);
// `
` element.
let p_node = div_node.first_child().unwrap();
let p_element = p_node.as_element().unwrap().to_matrix();
assert_matches!(p_element.element, MatrixElement::P);
assert!(p_element.attrs.is_empty());
// Text of `
` element.
let p_text_node = p_node.first_child().unwrap();
// `` element.
let em_node = p_text_node.next_sibling().unwrap();
let em_element = em_node.as_element().unwrap().to_matrix();
assert_matches!(em_element.element, MatrixElement::Em);
assert!(em_element.attrs.is_empty());
// `