GET-CONTEXT and count how many times it is in the order but
the CONTEXT variable itself. The returned number is therefore
minus one the occurences in the complete search-order.
usage:
ALSO EXTENSIONS CONTEXT? [IF] PREVIOUS [THEN]
ALSO DEF' DEFAULT-ORDER
: CONTEXT?
0 LVALUE _count
GET-ORDER 1- SWAP LVALUE _context
0 ?DO _context = IF 1 +TO _count THEN LOOP
_count
;