class Pet:
    def __init__(self, name, type, age):
        self.name = name
        self.type = type
        self.age = age
    def display_info(self):
        print(f"name: {self.name} type: {self.type} age: {self.age}")
    def have_birthday(self):
        self.age + 1
    def change_type(self, new_type):
        self.type = new_type