anchor.diff:  
   LINE_COMMENT
      :   '//' ~[\r\n]* -> skip
  -   ;+   ;
  
positive.code: 
  /*
   ANTLR4 grammar taken from TypeScript Documentation:
   https://github.com/Microsoft/TypeScript/blob/master/doc/spec.md#12.1.2
   and https://www.typescriptlang.org/docs/tutorial.html
  */
  
  grammar typescriptAmbientDeclarations;
  
  ambientDeclarationScript 
   : declarationSourceFile EOF
   ;
  
  
negative.code:  | methodSignature
   ;
  
  tupleType
   : '[' typeElementTypes ']'
   ;
  