make graphql typing for getDescription conform with graphql-js

types/graphql/index.d.ts

@@ -12,6 +12,7 @@
 //                 Tim Griesser <https://github.com/tgriesser>
 //                 Dylan Stewart <https://github.com/dyst5422>
 //                 Alessio Dionisi <https://github.com/adnsio>
+//                 Divyendu Singh <https://github.com/divyenduz>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -100,6 +101,9 @@ export {
     // Build a GraphQLSchema from a GraphQL schema language document.
     buildSchema,
 
+    // Get the description of an AST node
+    getDescription,
+
     // Extends an existing GraphQLSchema from a parsed GraphQL Schema
     // language AST.
     extendSchema,

types/graphql/utilities/buildASTSchema.d.ts

@@ -1,7 +1,13 @@
-import { DocumentNode, Location } from '../language/ast';
+import { DocumentNode, Location, StringValueNode } from '../language/ast';
 import { Source } from '../language/source';
 import { GraphQLSchema } from '../type/schema';
 
+type BuildSchemaOptions = {
+    assumeValid?: boolean;
+    allowedLegacyNames?: ReadonlyArray<string>;
+    commentDescriptions?: boolean;
+};
+
 /**
  * This takes the ast of a schema document produced by the parse function in
  * src/language/parser.js.
@@ -18,7 +24,10 @@ export function buildASTSchema(ast: DocumentNode): GraphQLSchema;
  * Given an ast node, returns its string description based on a contiguous
  * block full-line of comments preceding it.
  */
-export function getDescription(node: { loc?: Location }): string;
+export function getDescription(
+    node: { description?: StringValueNode; loc?: Location },
+    options: BuildSchemaOptions
+  ): string;
 
 /**
  * A helper function to build a GraphQLSchema directly from a source

types/graphql/utilities/index.d.ts

@@ -27,7 +27,7 @@ export { getOperationAST } from './getOperationAST';
 export { buildClientSchema } from './buildClientSchema';
 
 // Build a GraphQLSchema from GraphQL Schema language.
-export { buildASTSchema, buildSchema } from './buildASTSchema';
+export { buildASTSchema, buildSchema, getDescription } from './buildASTSchema';
 
 // Extends an existing GraphQLSchema from a parsed GraphQL Schema language AST.
 export { extendSchema } from './extendSchema';