code: function getImportantWords(node) {
    var words = {}
  
    visit(node, 'WordNode', visitor)
  
    return words
  
    function visitor(word, index, parent) {
      var match
      var stem
  
      if (isImportant(word)) {
        stem = stemNode(word)
        match = {
          node: word,
          index: index,
          parent: parent
        }
  
        if (!own.call(words, stem)) {
          words[stem] = {
            matches: [match],
            stem: stem,
            score: 1
          }
        } else {
          words[stem].matches.push(match)
          words[stem].score++
        }
      }
    }
  }
docs: Get most important words in `node`.