code: function getMutationScore(stats) {
      return {
          total: (stats.all - stats.survived) / stats.all,
          killed: stats.killed / stats.all,
          survived: stats.survived / stats.all,
          ignored: stats.ignored / stats.all,
          untested: stats.untested / stats.all
      };
  }
docs: Calculate the mutation score from a stats object.
  
  @param {object} stats - The stats from which to calculate the score
  @returns {{total: number, killed: number, survived: number, ignored: number, untested: number}}