anchor.diff:  
   // 16.36 Type Cast
   typeCast
  -  : asOperator type
  +  : asOperator dtype
     ;
   asOperator
     : 'as'
  
positive.code:   : metadata finalConstVarOrType identifier
    ;
  finalConstVarOrType
    : 'final' type?
    | 'const' type?
    | varOrType
    ;
  varOrType
    : 'var'
    | type
    ;
  
  initializedVariableDeclaration
  
negative.code:   ;
  // 16.35 Type Test
  typeTest
    : isOperator dtype
    ;
  isOperator
    : 'is' '!'?
  