Assertions are a way of breaking out of code when there is an error or an unexpected input.

Some languages throw exceptions and some treat it as a break point.



Task

Show an assertion in your language by asserting that an integer variable is equal to 42.




...
runerr(n,( expression ,"Assertion/error - message."))  # Throw (and possibly trap) an error number n if expression succeeds. 
...
stop(( expression ,"Assertion/stop - message."))       # Terminate program if expression succeeds.
...