anchor.diff:                  char ` word compiling if literal then BL word drop ; immediate
   : does>         ( -- ) // redirect the last new colon word.xt to after does>
                   [compile] ret \ dummy 'ret' mark for 'see' to know where is the end of a creat-does word
  -                r> [ s" push(function(){push(last().cfa)})" jsEvalNo , ] ! ; 
  +                \ r> [ s" push(function(){push(last().cfa)})" jsEvalNo , ] ! ; 
  +                r> py: push(last().cfa) ! ; 
   
                   <selftest>
                       *** .( ( ." .' s" s' s`
  
positive.code: 
  : [then]        ( -- ) // Conditional compilation [if] [else] [then]
                  ; immediate
  stop _stop_    
                  
  : ::            ( obj <foo.bar> ) // Simplified form of "obj py: pop().foo.bar" w/o return value
                  BL word py> tos().charAt(0)=='['||tos().charAt(0)=='(' if char pop() else  char pop(). then 
                  swap + compiling if jsFuncNo , else jsEvalNo then ; immediate
  : :>            ( obj <foo.bar> ) // Simplified form of "obj js> pop().foo.bar" w/return value
                  BL word js> tos().charAt(0)=='['||tos().charAt(0)=='(' if char pop() else  char pop(). then 
                  swap + compiling if jsFunc , else jsEval then ; immediate
  
  : (             ( <str> -- ) // Ignore the comment down to ')', can be nested but must be balanced
                  js> nextstring(/\(|\)/).str \ word 固定會吃掉第一個 character 故不適用。
  
negative.code: 
  code accept     push(False) end-code // ( -- str T|F ) Read a line from terminal. A fake before I/O ready.
  : refill        ( -- flag ) // Reload TIB from stdin. return 0 means no input or EOF
                  \ accept if [ s" push(function(){tib=pop();ntib=0})" jsEvalNo , ] 1 else 0 then ;
                  accept if py: vm.tib=pop();vm.ntib=0 1 else 0 then ;
  
  : [else] ( -- ) // 丟掉以下 TIB 到 "[else]" or "[then]" 為止，考慮了中間的 nested 結構。
                  1 \ ( [if] structure nested level )
  