code: function(svg, options) {
  
      // the svg element to render charts to
      this._svg = svg;
      this._attributes = options || {};
  
      // outer margins
      this._margin = {
          top: 20,
          bottom: 75,
          left: this._attributes.yScales.primary.displayOnAxis === 'left' ? 75 : 25,
          right: this._attributes.yScales.primary.displayOnAxis === 'left' ? 25 : 75
      };
  
  }
docs: Single Chart Layout
  @param {Object} svg the element
  @param {Object} options