Added exchanges map

src/utils/objectKeys.ts

@@ -0,0 +1,17 @@
+export type ObjectKeys<T extends object> = `${Exclude<keyof T, symbol>}`;
+
+/**
+A strongly-typed version of `Object.keys()`.
+This is useful since `Object.keys()` always returns an array of strings. This function returns a strongly-typed array of the keys of the given object.
+- [Explanation](https://stackoverflow.com/questions/55012174/why-doesnt-object-keys-return-a-keyof-type-in-typescript)
+- [TypeScript issues about this](https://github.com/microsoft/TypeScript/issues/45390)
+@example
+```
+const stronglyTypedItems = objectKeys({a: 1, b: 2, c: 3}); // => Array<'a' | 'b' | 'c'>
+const untypedItems = Object.keys(items); // => Array<string>
+```
+@category Improved builtin
+@category Type guard
+*/
+// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
+export const objectKeys = Object.keys as <Type extends object>(value: Type) => ObjectKeys<Type>[];