private void separate(boolean useComma) {
            if (!head && useComma) {
                out.append(',');
            } else {
                head = false;
            }
            if (!compact) {
                out.append("\n");
                for (int lvl = 0; lvl < level; lvl++) { out.append(" "); }
            }
        }
Renders the given value to the target stringbuilder with a given encoder.
This is useful to use an encoder where rendering of some value types is customized.
vespajlib/src/main/java/com/yahoo/data/access/simple/JsonRender.java