anchor.diff:  	;
   
   optional_int
  -	:	ASSIGN const
  +	:	ASSIGN constant
   	|	
   	;
   
  
positive.code: 	|	FOR ID ASSIGN index_expr TO index_expr DO stat_seq ENDDO SEMI
  	|	BREAK SEMI
  	|	RETURN expr SEMI
  	|	block
  	|	funct_call SEMI
  	;
  
  
negative.code: 	;
  
  optional_init
  	:	ASSIGN constant
  	|	
  	;
  
  