#python3 win10
def yy(background=0,bg=0):
	'''
	預設值引數別名的實現
	'''
	res = background if background != 0 else bg
	return res

print(yy(background=3))
print(yy(bg=3))

#------------

def yy1(background=0,bg=0):
	'''
	預設值引數別名的實現 方法1
	'''
	res = background and bg
	# res = background and bg  #也行,0為假

	# 相當於 res = (background and bg)
	# (background and bg) 邏輯連線,and,一假則假,(邏輯運算傾向於取'真',返回值是從左到右順序直到為真(and))
	return res

print(yy(background=3))
print(yy(bg=3))