code: function getEmptyLineNums(lines) {
      const emptyLines = lines.map((line, i) => ({
          code: line.trim(),
          num: i + 1
      })).filter(line => !line.code).map(line => line.num);
  
      return emptyLines;
  }
docs: ------------------------------------------------------------------------------ Helpers ------------------------------------------------------------------------------ 
  Return an array with with any line numbers that are empty.
  @param {Array} lines An array of each line of the file.
  @returns {Array} An array of line numbers.