Petite chez scheme confusing function with variable? (variable ___ is not bound) -

i've started learning scheme , i'm having trouble. using petite chez scheme (64-bit) windows. have been reading on examples using functions 'every' , 'keep' , 'accumulate' , understand built in , known petite (i.e. not have defined before use). when enter examples have read test them, error returned. example-

;; make nouns plural  (define (plural noun)  (if (equal? (last noun) ’y)  (word (bl noun) ’ies)  (word noun ’s)))   > (every plural ’(beatle turtle holly kink zombie))   ;; example input  (beatles turtles hollies kinks zombies)               ;; expected output 

instead receive error "variable every not bound". if 'every' being treated variable rather known function. receive same error when try examples 'keep' , 'accumulate'. coding correct assume (since copied book i'm reading). wrong in thinking these functions built in , not need defined or there other issue? hope can shed light on this.

the every procedure defined in srfi-1 , not part of standard language. refer project srfis available in chez scheme.

and besides, don't think every procedure you're looking for, want map - please check documentation first!

(map plural '(beatle turtle holly kink zombie))