and

Evaluates exprs one at a time, from left to right. If a form returns logical false (nil or false), and returns that valu...

false?

Returns true if x is the value false, false otherwise.

not

Returns true if x is logical false, false otherwise.

or

Evaluates exprs one at a time, from left to right. If a form returns a logical true value, or returns that value and doe...

true?

Returns true if x is the value true, false otherwise.