Example User entry and determine min and max values.

min_max.py

""" Program to accept list of numbers and return smallest and largest """

def main():
    print("Enter numbers.  Type 'done' for the number to compute min and max")
    smallest = largest = None
    while True:
        user_entry = input('enter a number ')
        if user_entry == 'done':
            break
        try:
            number = int(user_entry)
        except:
            print('invalid input')
            continue
        if smallest is None:
            smallest = number
        if largest is None:
            largest = number
        smallest = min(number, smallest)
        largest = max(number, largest)
        continue
    if smallest is not None:
        print(f"Maximum is {largest}")
        print(f"Minimum is {smallest}")
    else:
        print("You must enter at least one number")

if __name__ == '__main__':
    main()