In the previous example, I used the negation operator (!) in the expression !working_overtime, which can be read as “not working_overtime.” The negation operator can be used at the start of an expression; as an alternative, you can use the “not equals” (!= ) operator between the left and right sides of an expression:

negation.rb

!(1==1)         #=> false
1!=1            #=> false

Alternatively, you can use not instead of !:

not( 1==1 )        #=> false