anchor.diff:  	;
   
   funct_declaration
  -	:	ret_type FUNCTION ID LPAREN param_list RPAREN BEGIN block_list END SEMI
  +	:	ret_type FUNCTION ID LPAREN param_list RPAREN BEGIN block_list END SEMI -> ^(ID param_list block_list)
   	;
   	
   main_function
  
positive.code: 	|	(WHILE expr DO stat_seq ENDDO SEMI) -> ^(WHILE expr stat_seq)
  	|	(FOR ID ASSIGN range DO stat_seq ENDDO SEMI) -> ^(FOR range stat_seq)
  	|	BREAK SEMI -> BREAK
  	|	RETURN expr SEMI
  	|	block
  	|	funct_call SEMI -> funct_call
  	;
  
negative.code: 	;
  	
  param_list_tail
  	:	COMMA param param_list_tail -> ^(COMMA param param_list_tail)
  	|	
  	;
  	
  