Accept string and array in unload API

c3.js

@@ -5564,6 +5564,11 @@
     c3_chart_fn.unload = function (args) {
         var $$ = this.internal;
         args = args || {};
+        if (args instanceof Array) {
+            args = {ids: args};
+        } else if (typeof args === 'string') {
+            args = {ids: [args]};
+        }
         $$.unload($$.mapToTargetIds(args.ids), function () {
             $$.redraw({withUpdateOrgXDomain: true, withUpdateXDomain: true, withLegend: true});
             if (args.done) { args.done(); }

src/api.load.js

@@ -33,6 +33,11 @@ c3_chart_fn.load = function (args) {
 c3_chart_fn.unload = function (args) {
     var $$ = this.internal;
     args = args || {};
+    if (args instanceof Array) {
+        args = {ids: args};
+    } else if (typeof args === 'string') {
+        args = {ids: [args]};
+    }
     $$.unload($$.mapToTargetIds(args.ids), function () {
         $$.redraw({withUpdateOrgXDomain: true, withUpdateXDomain: true, withLegend: true});
         if (args.done) { args.done(); }