Tries to teach while, if else, variables, and equation in one file

study-01.py

# initialization of variables
x = None 
y = None

while not isinstance(x, int):
    print(isinstance(x, int))    
    try:
        x = input("Add your first number: ")
        x = int(x) # try to force x as number
    except ValueError:
        print("Please put a valid number.")

while not isinstance(x, int):
    print(isinstance(x, int))    
    try:
        y = input("Add your second number: ") 
        y = int(y) # try to force x as number
    except ValueError:
        print("Please put a valid number.")

choice = None
choices = ["add", "subtract", "divide", "multiply"]

while choice not in choices:
    choice = input("Type the option that you want to do for the two numbers: ")
    choice = choice.lower().strip()

message = ""
if choice == "add":
    z = x + y
    message = f"The summation of the two numbers are: {z}"

elif choice == "subtract": # else if
    z = x - y
    message = f"The difference of the two numbers are: {z}"
    
elif choice == "divide":
    z = x / y
    message = f"The division of the two numbers are: {z}"

elif choice == "multiply":
    z = x * y
    message = f"The product of the two numbers are: {z}"

print(message)