function afterPrefix(code) {
    const tail = self.events[self.events.length - 1]
    return tail &&
      tail[1].type === types.linePrefix &&
      tail[2].sliceSerialize(tail[1], true).length >= constants.tabSize
      ? atBreak(code)
      : nok(code)
  }
At start, after 1 or 4 spaces.

```markdown
> |     aaa
        ^
```

@type {State}