false -- a constant with the value of 0

okay=false 

The constant false can be assigned to variables which later appear in conditions (e.g. within an if-statement.
false may also be written as FALSE or even FaLsE.

input "Please enter a number between 1 and 10: " a 
if (check_input(a)) print "Okay" 

sub check_input(x) 
	if (x>10 or x<1) return false 
	return true 
end sub 

  The subroutine check_input checks its argument and returns true or false according to the outcome of the check.