JSONObject fo = a.getJSONObject(i);
String type = fo.has("type") ? fo.getString("type") : "list";
Facet facet = null;
if ("list".equals(type)) {
facet = new ListFacet();
} else if ("range".equals(type)) {
facet = new RangeFacet();
} else if ("timerange".equals(type)) {
facet = new TimeRangeFacet();
} else if ("scatterplot".equals(type)) {