function start(code) {
    if (code === codes.greaterThan) {
      const state = self.containerState

      assert(state, 'expected `containerState` to be defined in container')

      if (!state.open) {
        effects.enter(types.blockQuote, {_container: true})
        state.open = true
      }

      effects.enter(types.blockQuotePrefix)
      effects.enter(types.blockQuoteMarker)
      effects.consume(code)
      effects.exit(types.blockQuoteMarker)
      return after
    }

    return nok(code)
  }
Start of block quote.

```markdown
> | > a
    ^
```

@type {State}