Add full code for the render method for completeness

Author: jtpio

docs/source/examples/Widget Custom.ipynb

@@ -467,6 +467,11 @@
     "    this._emailInput.value = '[email protected]';\n",
     "    this._emailInput.disabled = true;\n",
     "    this.el.appendChild(this._emailInput);\n",
+    "    \n",
+    "    this.el.classList.add('custom-widget');\n",
+    "\n",
+    "    this.value_changed();\n",
+    "    this.model.on('change:value', this.value_changed, this);\n",
     "},\n",
     "```"
    ]