[] => never[], as empty tuple is invalid in TS@2

tstypes/language/visitor.d.ts

@@ -52,7 +52,7 @@ export type VisitFn<TAnyNode, TVisitedNode = TAnyNode> = (
 export type VisitorKeyMap<T> = { [P in keyof T]: ReadonlyArray<keyof T[P]> };
 
 export const QueryDocumentKeys: {
-  Name: [];
+  Name: never[]; // Should be empty tuple, but that requires TypeScript@3
 
   Document: ['definitions'];
   // Prettier forces trailing commas, but TS pre 3.2 doesn't allow them.
@@ -82,12 +82,12 @@ export const QueryDocumentKeys: {
     'selectionSet'
   ];
 
-  IntValue: [];
-  FloatValue: [];
-  StringValue: [];
-  BooleanValue: [];
-  NullValue: [];
-  EnumValue: [];
+  IntValue: never[]; // Should be empty tuple, but that requires TypeScript@3
+  FloatValue: never[]; // Should be empty tuple, but that requires TypeScript@3
+  StringValue: never[]; // Should be empty tuple, but that requires TypeScript@3
+  BooleanValue: never[]; // Should be empty tuple, but that requires TypeScript@3
+  NullValue: never[]; // Should be empty tuple, but that requires TypeScript@3
+  EnumValue: never[]; // Should be empty tuple, but that requires TypeScript@3
   ListValue: ['values'];
   ObjectValue: ['fields'];
   ObjectField: ['name', 'value'];