anchor.diff:  
   : [then]        ( -- ) // Conditional compilation [if] [else] [then]
                   ; immediate
  +                
  +: ::    ( obj <foo.bar> ) // Simplified form of "obj py: pop().foo.bar" w/o return value
  +        BL word <py> tos()[0]=='[' or tos()[0]=='(' </pyV> 
  +        if char pop() else char pop(). then 
  +        swap + compiling if </py> 
  +        else [compile] </py> then ; immediate
  +        
  +: :>    ( obj <foo.bar> ) // Simplified form of "obj js> pop().foo.bar" w/return value
  +        BL word <py> tos()[0]=='[' or tos()[0]=='(' </pyV>
  +        if char pop() else char pop(). then 
  +        swap + compiling if </pyV> 
  +        else [compile] </pyV> 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。
  
positive.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 ;
  
  : [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 )
  
negative.code:                 </selftest>
  
  : variable      ( <string> -- ) // Create a variable.
                  create 0 , py: last().type='colon-variable' ;
  : +!            ( n addr -- ) // Add n into addr, addr is a variable.
                  swap over @ swap + swap ! ;
  : ?             @ . ; // ( a -- ) print value of the variable.
  
                  <selftest>
  