Kata: Runtime errors are unpleasant for user experience. 

    This page will calculate factorial for a number. Try some negative numbers
    and see what happens. 

    Most of the time the developer doesn't know about it until a complaint is
    raised by a user. Use newrelic to track down these errors proactively and
    fix them.

    Check under Events -> Errors.

    Hint: IntegerField docs. 

Compute Factorial

Result =