anchor.diff:  goto_statement
   	:	'goto' plain_identifier ;
   	
  -while_statement	:	'while' '(' logical_expression ')' block ( 'continue' block )? ;
  +while_statement	:	'while' expression block ( 'continue' block )? ;
   
   if_statement
   	:	'if' '(' expression ')' block ( 'else' block )? ;
  
positive.code: 	;
  	
  side_effect_statement
  	:	assignment_statement
  	|	expression
  	;
  
  assignment_statement
  	:	primary_expression assignment_operator expression
  	;
  
  assignment_operator
  
negative.code: 
  expression
  	:	primary_expression
  	|	'!' expression
  	|	'-' expression
  	|	'(' expression ( '||' | '&&' | '==' | '!=' | '<' | '>' | '<=' | '>=' | '+' | '-' | '*' | '/' | '%' ) expression ')'
  	;
  
  primary_expression
  