Paste: Semantic error

USING: kernel math sequences namespaces ;
IN: search

: every-index ( seq ch -- index-seq ) swap   ! swap to ( ch seq )
                                      SYMBOL: i 0 i set { } ! The current index
                                      [ 2over i get swap index-from dup ] ! Make n/f n/f   ch i seq -- stack structure
                                      [ dup 1 + i set suffix ]  ! if true; updates i and adds index to array
                                      [ drop 2nip ] ! if false ! When done: drop seq and ch, so index-seg remain
                                      while ;