Update app.py

app.py

@@ -6,6 +6,8 @@ from dash import dcc, html
 external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
 
 app = dash.Dash(external_stylesheets=external_stylesheets)
+# Expose the Flask server instance
+server = app.server
 app.layout = html.Div([
     html.Div([
         html.Div([