add colab example md

colab-jupyterlab/README.md

@@ -0,0 +1,32 @@
+```python
+def expose(ngrok_authtoken):
+    import subprocess, threading, time
+    def bash(script): subprocess.run(script, shell=True)
+    def timer(done, s=45):
+        for i in range(s+1):
+          if done.is_set(): break
+          print(f'\rWait for ~ {s} seconds... \x1b[33m{i:>2} s', 
+                end='', flush=True)
+          time.sleep(1)
+
+    done = threading.Event()
+    threading.Thread(target=timer, args=(done,)).start()
+    bash('''
+        curl -s https://ngrok-agent.s3.amazonaws.com/ngrok.asc \
+        	| tee /etc/apt/trusted.gpg.d/ngrok.asc
+        echo "deb https://ngrok-agent.s3.amazonaws.com buster main" \
+        	| tee /etc/apt/sources.list.d/ngrok.list
+        apt-get update && apt-get install -y ngrok 
+        pip install jupyterlab pyngrok
+    ''')
+    from pyngrok import ngrok
+    ngrok.set_auth_token(ngrok_authtoken)
+    tunnel = ngrok.connect(8888).public_url
+    done.set()
+    print(f'\r{tunnel}', flush=True)
+    try: bash('jupyter lab --IdentityProvider.token=""')
+    finally: ngrok.disconnect(tunnel)
+
+expose(ngrok_authtoken='<YOUR_NGROK_AUTHTOKEN>')
+# https://dashboard.ngrok.com/get-started/your-authtoken
+```