Update app.py

app.py

@@ -64,7 +64,10 @@ def get_heatmap(sequence):
   plt.yticks(rotation=0)
   plt.xticks(y_tick_positions, y_tick_labels, rotation = 0)
 
-  return plt
+  fig = plt.gcf()
+  plt.close(fig)
+
+  return fig