code: function computeFixedSize(nodes, referenceSize) {
      var fixedSize = "";
      nodes.forEach(function (node) {
          var ratio = node.attribs['cell-ratio'];
          if (typeof ratio === 'undefined') return;
          var size = referenceSize + '*' + ratio;
          if (fixedSize != '') fixedSize += '+';
          fixedSize += size;
          node.size = size;
      });
      return fixedSize;
  }
docs: @param {array} nodes array of elements to align.
  @param {number} referenceSize for row in horizontal orientation, `referenceSize` is it's height.
  
  The weight defined a relative size, but a ratio force a fixed size.
  This  function compute  the  fixed sizes  returning  the total  and
  setting the fixed size on the `size` attribute of each node.