code: function getMaxValueByDate() {
              let keys = uniq(data.map(o => o.name));
              let maxValueByDate = d3Array.max(dataByDateFormatted, function(d){
                  let vals = keys.map((key) => d[key]);
  
                  return d3Array.sum(vals);
              });
  
              return maxValueByDate;
          }
docs: Computes the maximum sum of values for any date
  
  @return {Number} Max value