Function: not()
Negates an expression, i.e. returns true if the expression inside the brackets evaluates to false and vice versa.
The function not() takes one argument.
Returns false if expression evaluates to 1 or true and returns true otherwise.
Syntax
not(expression)
Examples
not(a < b)
not() returns true if a is greater than b and false if a is less than b.
not(1)
Returns false.
not(0)
Returns true.