Update app.py

app.py

@@ -255,7 +255,7 @@ def Mix_Melody(input_midi,
 
             for c in csong:
                 
-                pitches = [e[4] for e in c if c[6] == trg_patch]
+                pitches = [e[4] for e in c if e[6] == trg_patch]
                 
                 for cc in c: