Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/helpers/summon.ts

@@ -0,0 +1,39 @@
+import AuthUtils from "@dndbeyond/authentication-lib-js";
+
+import { getStt } from "./tokenUtils";
+
+export const getAuthHeaders = AuthUtils.makeGetAuthorizationHeaders({
+  madeGetShortTermToken: getStt,
+});
+
+/**
+ * A wrapper around fetch that adds the Authorization header and anything else
+ * that may need to be included in every request. If withCookies is true, the
+ * request will add the credentials: "include" option. Otherwise, this function
+ * should work exactly like the native fetch function.
+ *
+ * See https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
+ */
+export const summon = async (
+  input: RequestInfo | URL,
+  init?: RequestInit,
+  withCookies?: boolean
+) => {
+  // Get the Authorization headers from the auth token
+  const authHeaders = await getAuthHeaders();
+  // If withCookies is true, set the credentials to include
+  const credentials = withCookies && { credentials: "include" };
+  // If there is a body, set the Content-Type to application/json
+  const contentType = init?.body && { "Content-Type": "application/json" };
+
+  return window.fetch(input, {
+    ...(credentials as { credentials: RequestCredentials } | undefined),
+    ...init,
+    headers: {
+      ...authHeaders,
+      ...init?.headers,
+      ...contentType,
+      Accept: "application/json",
+    },
+  });
+};