— library syntax: begin <expression1> <expression2> ...

The <expression>s are evaluated sequentially from left to right, and the value(s) of the last <expression> is(are) returned. This expression type is used to sequence side effects such as input and output.

(define x 0)
     
     (begin (set! x 5)
            (+ x 1))                        ==>  6
     
     (begin (display "4 plus 1 equals ")
            (display (+ 4 1)))              ==>  unspecified
               and prints  4 plus 1 equals 5