code: function normalize(gj) {
      if (!gj || !gj.type) return null;
      var type = types[gj.type];
      if (!type) return null;
  
      if (type === 'geometry') {
          return {
              type: 'FeatureCollection',
              features: [{
                  type: 'Feature',
                  properties: {},
                  geometry: gj
              }]
          };
      } else if (type === 'feature') {
          return {
              type: 'FeatureCollection',
              features: [gj]
          };
      } else if (type === 'featurecollection') {
          return gj;
      }
  }
docs: Normalize a GeoJSON feature into a FeatureCollection.
  
  @param {object} gj geojson data
  @returns {object} normalized geojson data