Try this:
import curses
def Main(screen):
while True:
ch = screen.getch()
if ch == ord('q'):
break
elif ch == 27: # ALT was pressed
screen.nodelay(True)
ch2 = screen.getch() # get the key pressed after ALT
if ch2 == -1:
break
else:
screen.addstr(5, 5, 'ALT+'+str(ch2))
screen.refresh()
screen.nodelay(False)
curses.wrapper(Main)