一个函数作为另外一个函数的参数

def calc1(a, b, fn):
    return fn(a, b)


def add(x, y):
    return x + y


def minus(x, y):
    return x - y

# 回调函数
result1 = calc1(20, 10, add)  # 将add函数当作参数进行传递。
print(result1)  # 30

result2 = calc1(200, 100, minus)  # 将minus函数当作参数进行传递。
print(result2)  # 100

def calc2(a, b, fn):
    return fn(a, b)


result3 = calc1(10, 20, (lambda x, y: x + y))
print(result3)  # 30
result4 = calc2(200, 100, (lambda x, y: x - y))
print(result4)  # 40