# 8.2:  Validate Arguments.  Extend the previous program to validate user input.  Using try: and
# except:, trap an IndexError exception if one of the two arguments is missing - and have the
# program exit() with a Usage: string if the exception occurs (see output and note below).

# Exceptions:  trap an exception for missing arguments (IndexError when reading from sys.argv).
# (Remember to place as little code as possible in your try: block.)   If possible, print the
# program name in the Usage string (as shown below) using sys.argv[0].

# Expected Output:

# $ python myprog.py
# Usage: myprog.py [int1] [int2]
# 
# $ python myprog.py 5
# Usage: myprog.py [int1] [int2]
# 
# $ python myprog.py 5 hello
# Usage: myprog.py [int1] [int2]
# 
# $ python myprog.py 5 10
# 5 + 10 = 15

