anchor.diff:      ;
   
   quit_
  -    : (QUIT | 'Q') term
  +    : (QUIT) term
       ;
   
   new_
  -    : (NEW | 'N') SPACE* arglist
  +    : (NEW) SPACE* arglist
       ;
   
   break_
  -    : (BREAK | 'B')
  +    : (BREAK)
       ;
   
   do_
  -    : (DO | 'D') SPACE* identifier (LPAREN paramlist? RPAREN)?
  +    : (DO) SPACE* identifier (LPAREN paramlist? RPAREN)?
       ;
   
   BREAK
  
positive.code:     ;
  
  for_
      : FOR SPACE+ term EQUALS term COLON term SPACE* (command SPACE?)* COLON (term (LT | GT) term)
      ;
  
  halt_
      : (HALT | 'H')
      ;
  
  hang_
  
negative.code:     | LPAREN expression RPAREN
      ;
  
  condition
      : term
      | (term (LT | GT | EQUALS) term)
      ;
  
  comment
      : SEMICOLON ~(CR)*
      ;
  