Update app.py

app.py

@@ -153,7 +153,7 @@ def GenerateMIDI(num_tok, idrums, iinstr, progress=gr.Progress()):
 
     midi_plot = plt.figure(figsize=(14,5))
     midi_plot = plt.axes(title='Allegro Music Transformer Composition')
-    midi_plot = ax.set_facecolor('black')
+    midi_plot.set_facecolor('black')
     plt.scatter(x,y, c=c)
     plt.xlabel("Time")
     plt.ylabel("Pitch")