def max_num(num1, num2, num3):
     if num1 >= num2 and num1 >= num3:
         return num1
     elif num2 >= num1 and num2 >= num3:
         return num2
     else:
         return num3

print(max_num(300,4,5))

def is_dog(animal):
    if animal == "dog":
        print("This is a dog")
    else:
        print("This is not a dog")

is_dog("dog")