assignExpression:
   ternaryExpression (assignOperator assignExpression)?
   ;
assignOperator:
     '='
   | '>>>='
   | '>>='
   | '<<='
   | '+='
   | '-='
   | '*='
   | '%='
   | '&='
   | '/='
   | '|='
   | '^^='
   | '^='
   | '~='
   ;