bot_while_if

def do_calculation():
    print("lets " + command + " some numbers")
    input1 = input("Number 1> ")
    input2 = input("Number 2> ")
    number1 = int(input1)
    number2 = int(input2)
    if command == "add":
        result = number1 + number2
        operator = " + "
    elif command == "subtract":
        result = number1 - number2
        operator = " - "
    output = str(result)
    print(input1 + operator + input2 + " = " + output)
total = 0
meal_total=0
cash=0
finished=False


while finished==False:

    print("Hi, I am Marvin, your personal bot.")

    #asks and prints users name
    user_name = input ("What is your name? ")
    print("Welcome " + user_name )

    #input a calculation type
    command = input("How can I help? ")

    #when input add does an addition calculation
    if command == "add":
        do_calculation()

    #when input subtract does a suntraction calculation
    elif command == "subtract":
        do_calculation()

    #when input multiply does a multiply calculation
    elif command == "multiply":
        print("let's Multiply some numbers")
        input1 = input("Number 1> ")
        input2 = input("Number 2> ")
        number1 = int(input1)
        number2 = int(input2)
        result = number1 * number2
        output = str(result)
        print(input1 + " * " + input2 + " = " + output)

    #when input subtract does asubtraction calculation
    elif command == "subtract":
        print("let's subtract some numbers")
        input1 = input("Number 1> ")
        input2 = input("Number 2> ")
        number1 = int(input1)
        number2 = int(input2)
        result = number1 - number2
        output = str(result)
        print(input1 + " - " + input2 + " = " + output)

    #when input triangle calculates the are of a right angled triangle
    elif command == "triangle":
        print("let's find the area of a right angled triangle")
        input1 = input("Base of the triangle> ")
        input2 = input("Height of the triangle> ")
        number1 = int(input1)
        number2 = int(input2)
        result = (number1 * 0.5) * number2
        output = str(result)
        print("(" + input1 + " * 0.5) *" + input2 + " = " + output)
    # if neither add or subtract outputs an apology
    elif command == "average":
        how_many = input("How many numbers> ")
        how_many = int(how_many)
        for number_count in range(how_many):
            number = input("Enter number " + str(number_count) + "> ")
            total = total + int(number)
        result = total / how_many
        print("the average = " + str(result))
    elif command == "change":
        meal = []
        count= 0
        meal_items=int(input("How many items in your meal list?" ))


        for item_number in range(meal_items):
            item = int(input("How much was your first item? " + str(meal_items)+""))
            meal.append(item)
            count= count +1
            meal_total=int(meal_total)+int(item)


        output = str(count)

        print(meal)

        print("You have spent " + str(meal_total) + " on your meal.")

        cash= int(input("How much cash have you given?"))

        leftover = int(cash)-int(meal_total)
        print(("You should receive $" +str(leftover)+" in your change!"))

    elif command == "bye":
        finished = True


    else:
        print ("sorry I can't do that yet!!!")