docs: function computeBaseline(data) {
      var layerNum = data.length;
      var pointNum = data[0].length;
      var sums = [];
      var y0 = [];
      var max = 0;
      var temp;
      var base = {};
  
      for (var i = 0; i < pointNum; ++i) {
          for (var j = 0, temp = 0; j < layerNum; ++j) {
              temp += data[j][i][1];
          }
          if (temp > max) {
              max = temp;
          }
          sums.push(temp);
      }
  
      for (var k = 0; k < pointNum; ++k) {
          y0[k] = (max - sums[k]) / 2;
      }
      max = 0;
  
      for (var l = 0; l < pointNum; ++l) {
          var sum = sums[l] + y0[l];
          if (sum > max) {
              max = sum;
          }
      }
      base.y0 = y0;
      base.max = max;
  
      return base;
  }