code: function sortByFirst(valueArrays) {
    const firstValues = valueArrays[0];
    const indices = sortedIndices(firstValues);
    return valueArrays.map(function(values) {
      return indices.map(function(sortedIndex) {
        return values[sortedIndex];
      });
    });
  }
docs: Eg. sortByFirst([['b', 'a', 'c'], [1, 2, 3]]) = [['a', 'b', 'c'], [2, 1, 3]].
  @param  {Array[]} valueArrays The array of arrays of values to sort.
  @return {Array[]} The values sorted by the first column.