Minor tweaks to the custom widget tutorial

Author: jtpio

docs/source/examples/Widget Custom.ipynb

@@ -370,8 +370,7 @@
     "The TypeScript cookiecutter generates a file `src/widget.ts`. Open the file and rename `ExampleModel` to `EmailModel` and `ExampleView` to `EmailView`:\n",
     "\n",
     "```typescript\n",
-    "export\n",
-    "class EmailModel extends DOMWidgetModel {\n",
+    "export class EmailModel extends DOMWidgetModel {\n",
     "  defaults() {\n",
     "    return {...super.defaults(),\n",
     "      _model_name: EmailModel.model_name,\n",
@@ -392,14 +391,13 @@
     "  static model_name = 'EmailModel';\n",
     "  static model_module = MODULE_NAME;\n",
     "  static model_module_version = MODULE_VERSION;\n",
-    "  static view_name = 'EmailView';   // Set to null if no view\n",
-    "  static view_module = MODULE_NAME;   // Set to null if no view\n",
+    "  static view_name = 'EmailView';\n",
+    "  static view_module = MODULE_NAME;\n",
     "  static view_module_version = MODULE_VERSION;\n",
     "}\n",
     "\n",
     "\n",
-    "export\n",
-    "class EmailView extends DOMWidgetView {\n",
+    "export class EmailView extends DOMWidgetView {\n",
     "  render() {\n",
     "    this.el.classList.add('custom-widget');\n",
     "\n",
@@ -445,7 +443,7 @@
     "Then, add the following logic for the `render` method:\n",
     "\n",
     "```typescript\n",
-    "render: function() { \n",
+    "render() { \n",
     "    this._emailInput = document.createElement('input');\n",
     "    this._emailInput.type = 'email';\n",
     "    this._emailInput.value = '[email protected]';\n",
@@ -501,7 +499,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "We want to be able to avoid user to write an invalid email address, so we need a validator using traitlets.\n",
+    "We want to be able to avoid the user to write an invalid email address, so we need a validator using traitlets.\n",
     "\n",
     "```python\n",
     "from ipywidgets import DOMWidget, ValueWidget, register\n",
@@ -570,8 +568,7 @@
     "By replacing the string literal with a call to `model.get`, the view will now display the value of the back end upon display.  However, it will not update itself to a new value when the value changes.\n",
     "\n",
     "```typescript\n",
-    "export\n",
-    "class EmailView extends DOMWidgetView {\n",
+    "export class EmailView extends DOMWidgetView {\n",
     "  render() {\n",
     "    this._emailInput = document.createElement('input');\n",
     "    this._emailInput.type = 'email';\n",
@@ -604,8 +601,7 @@
     "To get the view to update itself dynamically, register a function to update the view's value when the model's `value` property changes.  This can be done using the `model.on` method.  The `on` method takes three parameters, an event name, callback handle, and callback context.   The Backbone event named `change` will fire whenever the model changes.  By appending `:value` to it, you tell Backbone to only listen to the change event of the `value` property (as seen below).\n",
     "\n",
     "```typescript\n",
-    "export\n",
-    "class EmailView extends DOMWidgetView {\n",
+    "export class EmailView extends DOMWidgetView {\n",
     "  render() {\n",
     "    this._emailInput = document.createElement('input');\n",
     "    this._emailInput.type = 'email';\n",
@@ -639,8 +635,7 @@
     "This allows us to update the value from the Python kernel to the views. Now to get the value updated from the front-end to the Python kernel (when the input is not disabled) we can do it using the `model.set` method.\n",
     "\n",
     "```typescript\n",
-    "export\n",
-    "class EmailView extends DOMWidgetView {\n",
+    "export class EmailView extends DOMWidgetView {\n",
     "  render() {\n",
     "    this._emailInput = document.createElement('input');\n",
     "    this._emailInput.type = 'email';\n",