>> x = 23 == 23 && ! y = 42 == 23     #=> false
>> [x,y]                              #=> [false, true]
>> x = 23 == 23 and not y = 42 == 23  #=> false
>> [x,y]                              #=> [true, true]

... a coding style that personally gives me the hibby-jibbies, but at
least you have the option of playing with it.