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: based-exec ( i*x base xt -- j*x )                                             
   base @ >r  swap base !  execute  r> base ! ;                                 
: eval-word ( i*x -- j*x )                                                      
   parse-word evaluate ;                                                        
: based-eval ( newbase "word" -- )                                              
   ['] eval-word based-exec ;                                                   
: based ( newbase -- )                                                          
   state @ if                                                                   
      ' postpone literal postpone based-exec                                    
   else                                                                         
      based-eval                                                                
   then ; immediate                                                             
: _ ( "number" -- )                                                             
   state @ if                                                                   
      -2 cells allot here cell+ @                                               
   then  based-eval ; immediate                                                 
                                                                                
: test2 2 _ 10 . ;                                                              
: test16 16 _ 10 . ;                                                            
: hex. 16 based . ;                                                             
: oct. 8 based . ; 
test2  2 _ 10 . cr                                                              
test16  16 _ 10 . cr                                                            
255 hex.  255 16 based . cr                                                     
255 oct.  255 8 based . cr