anchor.diff:  	;
   	
   side_effect_statement
  -	:	assignment_statement
  +	:	primary_expression assignment_operator expression
  +	|	primary_expression ( '++' | '--' )
   	|	expression
  -	;
  -
  -assignment_statement
  -	:	primary_expression assignment_operator expression
   	;
   
   assignment_operator
  
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
  