: _&
    CREATE , DOES>
    ( n1 f n2 cell )
    ROT NOT IF 2DROP 0 EXIT THEN ( n1 true )
    _|&
;

( All words below have this signature:
  n1 f n2 -- n1 f )
' = _| |=
' = _& &=
' > _| |>
' > _& &>
' < _| |<
' < _& &<