Prevent console line advancing on user input

[anonymouse]

Wondering if this is possible? Ask a user at input and wait for 
response:

write("Is the sky blue? ");
readf!" %s\n"(response);

If the user's response is correct, I'd like to change the color 
of provided response to indicate it was correct then advance to 
the next line and ask a different question.

If the user's response is incorrect, I'd like to clear the line 
and repeat the question without advancing down the screen 
vertically.

I'm assuming it can be done by intercepting all input before the 
console processes them and outputting a '\r', a blank line the 
length of the screen, and another '\r' to get back to the 
beginning before reprinting the question. But I have no idea how 
to intercept the raw input.

Would appreciate any pointers.
Thanks
--anonymouse