code: function extractStyleInfo(psd/*, opts*/) {
          var SON = {};
          var layers = psd.layers;
          _classnames = [];
          _psd = psd;
          SON.layers = [];
          layers.forEach(function (layer) {
              var s = extractLayerStyleInfo(layer);
              if (s !== undefined) {
                  SON.layers.push(s);
              }
          });
  
          return SON;
      }
docs: Return a SON document for the specified document info
  
  @param {Object} psd document retrieved from Generator.getDocumentInfo()
  
  @return {Object} The SON document for the specified Generator document
  
  Note: This API should be considered private and may be changed/removed at any
  time with only a bump to the "patch" version number of generator-core.
  Use at your own risk.