Horribly noobful string question

[SeNTry]

Hi Everyone,

My first post here as I just begin to learn programming in general and 
python in particular.  I have all the noobie confused questions, but as I 
work thru the tutorials I'm sure I'll find most my answers.

This one is eluding me tho... I am working in the tutorials, writing scripts 
as presented and then modifying and expanding on my own to try to learn. 
I'm working with one that asks the user to 'guess a number I'm thinking', 
and with simple while loop, flow control and operands, returning an answer 
to guess again or you got it.  I've added a 'playagain' function I've got 
working, but what I want is to stop the program from crashing when someone 
enters a string value instead of a int value.  I know strings are immutable, 
and they can be changed to an int equivalent, but I just want the script to 
recognize the input as a string and print a simple "that's not a number, try 
again' type of message.  I can't find the syntax to include in the 
if/elif/else block to include a line that says something like,

elif guess == <string>
    print "that's not a number! please guess again!"

I know that's not right, but can you see what I'm looking for and offer a 
suggestion?

Thanks in advance all.