define events as hash instead of method

.gitignore

@@ -110,3 +110,11 @@ dmypy.json
 
 # OSX files
 .DS_Store
+
+# pycharm 
+.idea/
+
+# yarn build related 
+.yarn/
+.yarnrc.yml
+yarn.lock

src/fullscreen.ts

@@ -89,11 +89,7 @@ export class FullscreenButtonView extends DOMWidgetView {
   /**
    * Dictionary of events and handlers
    */
-  events(): { [e: string]: string } {
-    // TODO: return typing not needed in Typescript later than 1.8.x
-    // See http://stackoverflow.com/questions/22077023/why-cant-i-indirectly-return-an-object-literal-to-satisfy-an-index-signature-re and https://github.com/Microsoft/TypeScript/pull/7029
-    return { click: '_handle_click' };
-  }
+  events: { [e: string]: string } = { click: '_handle_click' };
 
   /**
    * Handles when the button is clicked.