import machine
import time

# Function to perform addition
def add(x, y):
    return x + y

# Function to perform subtraction
def subtract(x, y):
    return x - y

# Function to perform multiplication
def multiply(x, y):
    return x * y

# Function to perform division
def divide(x, y):
    if y == 0:
        return "Error: Division by zero"
    else:
        return x / y

# Function to read a number from user input
def read_number(prompt):
    try:
        return float(input(prompt))
    except ValueError:
        print("Invalid input. Please enter a number.")
        return read_number(prompt)

# Function to read an operator from user input
def read_operator():
    operators = ['+', '-', '*', '/']
    while True:
        op = input("Enter an operator (+, -, *, /): ")
        if op in operators:
            return op
        else:
            print("Invalid operator. Please enter one of '+', '-', '*', '/'.")

# Main function
def main():
    while True:
        # Read input numbers and operator
        num1 = read_number("Enter the first number: ")
        num2 = read_number("Enter the second number: ")
        operator = read_operator()

        # Perform calculation based on operator
        if operator == '+':
            result = add(num1, num2)
        elif operator == '-':
            result = subtract(num1, num2)
        elif operator == '*':
            result = multiply(num1, num2)
        elif operator == '/':
            result = divide(num1, num2)

        # Display result
        print("Result:", result)

        # Ask user if they want to perform another calculation
        choice = input("Do you want to perform another calculation? (yes/no): ")
        if choice.lower() != 'yes':
            print("Goodbye!")
            break

# Run the main function
if __name__ == "__main__":
    main()