= function compares numbers according to "equal" predicate. Result is true if every specified number is equal to each other, otherwise result is false.

(= 1 2) => NIL
(= 2 1) => NIL
(= 2 2.001) => NIL
(= 2 2) => T
(= 2 2.0) => T
(= 0.0 -0.0) => T
(= #c(1.2 4.5) #c(1.2 4.5)) => T

(= 1 2 3 4 5) => NIL
(= 4 4 4 3 4) => NIL
(= 4 4 4 4 4) => T
(= 4 4 4 4.0 4) => T
(= 5) => T