V3 AddSubAvgTotal Abstraction and Forced Numerics Complete

##   V3 Add-Subtract-Average-Total with Abstraction and Numeric checks                          ##
##   Finished Add, Subtract, Average and Total Functions.                                       ##
##   Used Abstraction to exploit Functions thus simplifying the base logic                      ##
##   Further refined by insisting that numeric values must be entered for all function input    ##
##   There still remains the problem of ending the numbers input into the Total function        ##
##   Currently the number 0 is used to end the input whereas I'd prefer either "End" or "end"   ##

# Function to ensure input is numeric
def inputNumber(message):
    while True:
        try:
            userInput = int(input(message))
        except ValueError:
            print("Not an integer! Try again.")
            continue
        else:
            return userInput
            break

# Function used for the Add and Subtract operations
def do_calculation():
    print("lets " + command + " some numbers")
    userInput = inputNumber("Number 1> ")
    number1 = userInput
    userInput = inputNumber("Number 2> ")
    number2 = userInput
    if command == "add":
        result = number1 + number2
        operator = " + "
    elif command == "subtract":
        result = number1 - number2
        operator = " - "
    output = str(result)
    print(str(number1) + operator + str(number2) + " = " + output)

# Function used for the Average operation
def do_average():
    numbers = []
    userInput = inputNumber("how many numbers would you like to find the average for? ")
    how_many = userInput
    for item_number in range(how_many):
        display_number = item_number + 1
        item = inputNumber("what is your number " + str(display_number) + "? ")
        numbers.append(item)
    count = 0
    for item in numbers:
        count = count + item
    result = count / how_many
    print("No. of items entered :  " + str(len(numbers)))
    print("The average of your " + str(len(numbers)) + " items is " + str(result))

# Function which implements the Total operation
def do_total():
    item = int(1)
    item_number = int(0)
    total = int(0)
    while item != 0:
        display_number = item_number + 1
        item = inputNumber("what is your number " + str(display_number) + "?  or type the number 0 to end ")
        if item != 0:
            total = total + int(item)
            item_number = item_number + 1
    print("The total of the " + str(item_number) + " numbers you entered is " + str(total))

print("Would you like to add or subtract two numbers or find the average or total of multiple numbers?")
command = input("Enter 'add', 'subtract', 'average' or 'total' > ")

if command == "add":
    do_calculation()

elif command == "subtract":
    do_calculation()

elif command == "average":
    do_average()

elif command == "total":
    do_total()

else:
    print("Try again and enter 'add', 'subtract', 'average' or 'total' ")
    print("Bye")