anchor.diff:  
   expression
   	:	primary_expression
  -	|	arithmetic_expression
  -	|	logical_expression
  +	|	'!' expression
  +	|	'-' expression
  +	|	'(' expression ( '||' | '&&' | '==' | '!=' | '<' | '>' | '<=' | '>=' | '+' | '-' | '*' | '/' | '%' ) expression ')'
   	;
   
   primary_expression
  
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 ( ',' expression )*
  	;
  
  //
  // Basics:
  //
  