class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

def new_person(name):
    p = Person(name, 42)
    return p

if __name__ == "__main__":
    # This syntax creates a new instance of the class.
    print(Person("Bob", 20))

    # You can name the fields when initializing a class.
    print(Person(name="Alice", age=30))

    # Omitted fields will be set to the defaults defined in the `__init__` method.
    print(Person(name="Fred", age=0))

    # Getting a reference to the object
    print(f"&{Person(name='Ann', age=40)}")

    # It’s idiomatic to encapsulate new class creation in functions
    print(new_person("Jon"))

    # Access class fields with a dot.
    s = Person(name="Sean", age=50)
    print(s.name)

    # You can also use dots with object instances.
    sp = s
    print(sp.age)

    # Objects are mutable.
    sp.age = 51
    print(sp.age)

    # If a class type is only used for a single value, we can use an anonymous class.
    Dog = type("Dog", (object,), {"name": "Rex", "isGood": True})
    dog = Dog()
    print(dog)

<__main__.Person object at 0x7f3e784708e0>
<__main__.Person object at 0x7f3e78470e80>
<__main__.Person object at 0x7f3e78470df0>
&<__main__.Person object at 0x7f3e78470e50>
<__main__.Person object at 0x7f3e78470ca0>
Sean
50
51
<__main__.main.<locals>.Dog object at 0x7f3e78470fd0>