function start(code) {
      // Always populated by defaults.
      assert(
        self.parser.constructs.disable.null,
        'expected `disable.null` to be populated'
      )

      // To do: `enter` here or in next state?
      effects.enter(types.codeFencedFence)
      return markdownSpace(code)
        ? factorySpace(
            effects,
            beforeSequenceClose,
            types.linePrefix,
            self.parser.constructs.disable.null.includes('codeIndented')
              ? undefined
              : constants.tabSize
          )(code)
        : beforeSequenceClose(code)
    }
Before closing fence, at optional whitespace.

```markdown
  | ~~~js
  | alert(1)
> | ~~~
    ^
```

@type {State}