: first-subseq ( seq separators -- n separator )
tuck
- [ [ subsequence-starts ] dip 2array ] withd map-index sift-keys
+ [ [ subseq-index ] dip 2array ] withd map-index sift-keys
[ drop f f ] [ [ first ] infimum-by first2 rot nth ] if-empty ;
: multisplit ( string separators -- seq )