note:
   ┌─ test.html:1:17
   │
 1 │ this is a tag: <h1>test</h1>
   │                 ^^       ^^ end tag
   │                 │
   │                 start tag
   ·
 5 │ Attribute values can be quoted: <input name = 'age' type = "number">
   │                                        ^^^^    ^^^  ^^^^    ^^^^^^ attr value
   │                                        │       │    │
   │                                        │       │    attr name
   │                                        │       attr value
   │                                        attr name
 6 │
 7 │ But you cannot put attributes everywhere: </nope data=foobar>
   │                                                  ^^^^ end-tag-with-attributes
 8 │
 9 │ Please mind the gap: < test
   │                       ^ invalid-first-character-of-tag-name
10 │
11 │ The pirate says &arrrrr;
   │                        ^ unknown-named-character-reference
12 │
13 │ Does this open two pages? <a href=foo.html href=bar.html>click me</a>
   │                                            ^^^^ duplicate-attribute
14 │
15 │ Do you start or do you end? </yes/>
   │                                   ^ end-tag-with-trailing-solidus