anchor.diff:  //
   
   declaration
  -	:	data_declaration | subroutine_declaration ;
  +	:	data_declaration
  +	|	subroutine_declaration
  +	;
   
   data_declaration
  -	:	constant_declaration | variable_declaration;
  -	
  -constant_declaration
  -	:	'const' type_name plain_identifier '=' literal ';';
  -
  -variable_declaration
  -	:	'var' type_name plain_identifier_list ( '=' expression )? ';';
  +	:	'const' type_name plain_identifier '=' literal ';'
  +	|	'var' type_name plain_identifier_list ( '=' expression )? ';'
  +	;
   
   plain_identifier_list
  -	:	plain_identifier ( ',' plain_identifier )* ;
  +	:	plain_identifier ( ',' plain_identifier )*
  +	;
   
   //
   // Definitions:
  
positive.code: goto_statement
  	:	'goto' plain_identifier ;
  	
  while_statement	:	'while' '(' logical_expression ')' block ( 'continue' block )? ;
  
  if_statement
  	:	'if' '(' expression ')' block ( 'else' block )? ;
  
negative.code: 
  expression
  	:	primary_expression
  	|	'!' expression
  	|	'-' expression
  	|	'(' expression ( '||' | '&&' | '==' | '!=' | '<' | '>' | '<=' | '>=' | '+' | '-' | '*' | '/' | '%' ) expression ')'
  	;
  
  primary_expression
  