Usage: UNLESS (<expression>) <then-statement>
       UNLESS (<expression>) {<then-statements>} [{<else-statements>}]

  UNLESS is the opposite of IF.  It basically just reverses the order
  that the THEN and ELSE statements are executed.  If <expression> returns
  false, the THEN portion is executed; if it returns true, and an ELSE
  portion is present, the ELSE portion is executed.  For example:

    UNLESS ( foo == 1 ) ...

  is the same as

    IF ( !(foo == 1) ) ...

  Both IF and UNLESS use the same command syntax; see the helpfile for IF
  for more information.

See Also:
  @
  IF
  UNTIL
  WHILE
  expressions
