The logical Not operator.
[If] Not expression
Not is a logical operator whose result is the boolean (True/False) opposite of the following expression's boolean evaluation.
Where the expression to be evaluated is True, applying Not to the expression will evaluate as False.
Where the expression to be evaluated is False, applying Not to the expression will evaluate as True.
Not is often used as a shorthand to check for False expression evaluation results.
This examples checks for the non-existence of bullets before firing. Because Not bullets evaluates as True, we execute the 'no bullets' line.
If bullets were any non-zero value, the expression Not bullets would evaluate as False and the Else statement would be executed.
"Splut... no bullets"