Update app.py

app.py

@@ -21,8 +21,12 @@ ui.input_select("center", "Center", choices=list(city_centers.keys()))
 
 @render_widget
 def map():
-    Map = ipyleaflet.Map(zoom=4)
-    return Map
+    m = ipyleaflet.Map(zoom=4)
+    tile = geemap.ee_tile_layer(dem, vis_params, "SRTM DEM")
+    url = tile.url
+    layer = ipyleaflet.TileLayer(url, attribution="Google", name="DEM")
+    m.add(layer)
+    return m
 
 @reactive.effect
 def _():