I took an early opportunity of testing that statement . . .
--Agatha Christie, The Mysterious Affair at Styles (1920), Chapter 12
An if-then statement is executed by first evaluating the Expression. If evaluation
of the Expression completes abruptly for some reason, the if-then statement
completes abruptly for the same reason. Otherwise, execution continues by making a choice based on the resulting value:
true, then the contained Statement is executed; the if-then statement completes normally only if execution of the Statement completes normally.
false, no further action is taken and the if-then statement completes normally.