anchor.diff:  switchStmt: exprSwitchStmt | typeSwitchStmt;
   
   exprSwitchStmt:
  -	SWITCH (expression | ((simpleStmt? eos)? expression?)) L_CURLY exprCaseClause* R_CURLY;
  +	SWITCH (expression?
  +					| simpleStmt? eos expression?
  +					) L_CURLY exprCaseClause* R_CURLY;
   
   exprCaseClause: exprSwitchCase COLON statementList?;
   
  
positive.code: 	| IMAGINARY_LIT
  	| RUNE_LIT;
  
  operandName: IDENTIFIER (DOT IDENTIFIER)?;
  
  qualifiedIdent: IDENTIFIER DOT IDENTIFIER;
  
  
negative.code: 
  expression:
  	primaryExpr
  	| unary_op = (
  		PLUS
  		| MINUS
  		| EXCLAMATION
  		| CARET
  		| STAR
  		| AMPERSAND
  		| RECEIVE
  	) expression
  	| expression mul_op = (
  		STAR
  		| DIV
  