def hello():
    print("Hello, World!")

print(callable(hello))  # 输出为True，表示函数hello是可调用的

class Calculator:
    def __init__(self):
        self.result = 0

    def add(self, num1, num2):
        self.result = num1 + num2

print(callable(Calculator))  # 输出为True，表示类Calculator是可调用的

class Calculator:
    def __init__(self):
        self.result = 0

    def add(self, num1, num2):
        self.result = num1 + num2

calculator = Calculator()
print(callable(calculator))  # 输出为False，表示实例对象calculator不是可调用的