code: function daleChallGradeLevel(score) {
    score = Math.floor(score)
  
    if (score < 5) {
      score = 4
    } else if (score > 9) {
      score = 10
    }
  
    return gradeMap[score].concat()
  }
docs: Mapping between a dale-chall score and a U.S. grade level.