: (4sequence) ( obj1 obj2 obj3 obj4 seq -- seq )
[ 3 swap set-nth-unsafe ] keep (3sequence) ; inline
-PRIVATE>
-
: head-to-index ( seq to -- zero to seq ) [ 0 ] 2dip swap ; inline
: index-to-tail ( seq from -- from length seq ) swap [ length ] keep ; inline
+PRIVATE>
+
: from-tail ( seq n -- seq n' ) [ dup length ] dip - ; inline
: 1sequence ( obj exemplar -- seq )