hunk.code_window:     const { document } = state
       const schema = editor.getSchema()
       const offsetKey = OffsetKey.findKey(element, offset)
       const { key } = offsetKey
       const node = document.getDescendant(key)
       const decorators = document.getDescendantDecorators(key, schema)
       const ranges = node.getRanges(decorators)
  
hunk.labels: keep keep add keep keep keep keep
hunk.after_edit:     if (!offsetKey) return null
  
hunk.file_path: src/components/content.js
hunk.type: add
file: 
  import assert from 'assert'
  
  export default function (state) {
    const { document, selection } = state
    const texts = document.getTexts()
    const first = texts.first()
    const range = selection.merge({
      anchorKey: first.key,
      anchorOffset: 0,
      focusKey: first.key,
      focusOffset: 0
    })
  
    const next = state
      .transform()
      .moveTo(range)
      .deleteForward(3)
      .apply()
  
    assert.deepEqual(
      next.selection.toJS(),
      range.collapseToStart().toJS()
    )
  
    return next
  }
  