Python jednoduchá kalkulačka

# Jednoduchá kalkulačka v Pythonu
 
# This function adds two numbers
def add(x, y):
    return x + y
 
# This function subtracts two numbers
def subtract(x, y):
    return x - y
 
# This function multiplies two numbers
def multiply(x, y):
    return x * y
 
# This function divides two numbers
def divide(x, y):
    return x / y
 
 
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
 
while True:
    # take input from the user
    choice = input("Enter choice(1/2/3/4): ")
 
    # check if choice is one of the four options
    if choice in ('1', '2', '3', '4'):
        num1 = float(input("Enter first number: "))
        num2 = float(input("Enter second number: "))
 
        if choice == '1':
            print(num1, "+", num2, "=", add(num1, num2))
 
        elif choice == '2':
            print(num1, "-", num2, "=", subtract(num1, num2))
 
        elif choice == '3':
            print(num1, "*", num2, "=", multiply(num1, num2))
 
        elif choice == '4':
            print(num1, "/", num2, "=", divide(num1, num2))
       
        # check if user wants another calculation
        # break the while loop if answer is no
        next_calculation = input("Let's do next calculation? (yes/no): ")
        if next_calculation == "no":
          break
   
    else:
        print("Invalid Input")