diff --git a/src/resolver.ts b/src/resolver.ts
index 2eeba49..856f031 100644
--- a/src/resolver.ts
+++ b/src/resolver.ts
@@ -1,34 +1,31 @@
-// This file simulates a full-fledged GraphQL resolver in a simplified context for a take-home test.
 import {userData1, userData2} from "./data";
 import {DataSource, User} from "./types";
 
 export function getUsers(): User[] {
-    // Task: Combine userData1 and userData2 into a single array and return users normalized to match the schema.
-    // Hint: You may want to use the normalizeUser function on each user object before returning the final array.
     const rawUsers = [...userData1, ...userData2];
-
-    return []; // TODO: Replace this with the normalized list of users.
+    const normalizedUsers = rawUsers.map(normalizeUser);
+    return normalizedUsers;
 }
 
 export function getUserById(id: string | number): User | null {
-    // Task: Implement this function to return a user by their ID from the correct data source.
-    // Hint: Check the type of `id` to determine whether to search in userData1 or userData2.
-    // userData1 contains UUIDs (strings), while userData2 contains numerical IDs.
+    const user = typeof id === 'string'
+        ? userData1.find(userData => userData.id === id)
+        : userData2.find(userData => userData.id === id);
+
+    if (user) {
+        return normalizeUser(user);
+    }
 
-    return null; // TODO: Implement the logic to find and return the appropriate user.
+    return null;
 }
 
-// This function is intended to normalize user data from different formats into a uniform schema.
 function normalizeUser(user: any): User {
-    // Task: Adapt this function to convert an input user object into the format specified below.
-    // Hint: Map properties from both userData1 and userData2 to this uniform schema.
-    // Example mapping: `first` or `first_name` should map to `firstName`.
     return {
-        id: '', // TODO: Set this to the user's id.
-        firstName: '', // TODO: Set this to the user's first name, considering both 'first' and 'first_name'.
-        lastName: '', // TODO: Set this to the user's last name, considering both 'last' and 'last_name'.
-        emailAddress: '', // TODO: Set this to the user's email address, considering both 'email' and 'email_address'.
-        phoneNumber: '', // TODO: Set this to the user's phone number, considering both 'phone' and 'phone_number'.
-        source: DataSource.DATA_SOURCE_1 // Hint: Determine the source based on the ID type (string for DATA_SOURCE_1, number for DATA_SOURCE_2).
+        id: user.id,
+        firstName: user.first || user.first_name || '',
+        lastName: user.last || user.last_name || '',
+        emailAddress: user.email || user.email_address || '',
+        phoneNumber: user.phone || user.phone_number || '',
+        source: typeof user.id === 'string' ? DataSource.DATA_SOURCE_1 : DataSource.DATA_SOURCE_2
     };
 }
diff --git a/src/types.ts b/src/types.ts
index ddc452a..c94eefd 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -9,6 +9,6 @@ export interface User {
 }
 
 export enum DataSource {
-    DATA_SOURCE_1,
-    DATA_SOURCE_2
+    DATA_SOURCE_1 = "DATA_SOURCE_1",
+    DATA_SOURCE_2 = "DATA_SOURCE_2",
 }
diff --git a/test/resolver.test.ts b/test/resolver.test.ts
index aeb34e5..a2d2c9b 100644
--- a/test/resolver.test.ts
+++ b/test/resolver.test.ts
@@ -23,16 +23,16 @@ describe('Resolver Tests', () => {
             const uuid = 'c3d504e3-4f82-4e28-8db9-b3157647c8c1';
             const user = getUserById(uuid);
             expect(user).not.toBeNull();
-            expect(user.id).toEqual(uuid);
-            expect(user.source).toEqual(DataSource.DATA_SOURCE_1);
+            expect(user?.id).toEqual(uuid);
+            expect(user?.source).toEqual(DataSource.DATA_SOURCE_1);
         });
 
         it('should return a user by numeric ID from DataSource.DATA_SOURCE_2', () => {
             const numericId = 1;
             const user = getUserById(numericId);
             expect(user).not.toBeNull();
-            expect(user.id).toEqual(numericId);
-            expect(user.source).toEqual(DataSource.DATA_SOURCE_2);
+            expect(user?.id).toEqual(numericId);
+            expect(user?.source).toEqual(DataSource.DATA_SOURCE_2);
         });
 
         // Test to verify that the correct data source is used based on the ID type
@@ -42,10 +42,10 @@ describe('Resolver Tests', () => {
             const userFromUuid = getUserById(uuid);
             const userFromNumericId = getUserById(numericId);
 
-            expect(userFromUuid.source).toEqual(DataSource.DATA_SOURCE_1);
-            expect(typeof userFromUuid.id).toBe('string');
-            expect(userFromNumericId.source).toEqual(DataSource.DATA_SOURCE_2);
-            expect(typeof userFromNumericId.id).toBe('number');
+            expect(userFromUuid?.source).toEqual(DataSource.DATA_SOURCE_1);
+            expect(typeof userFromUuid?.id).toBe('string');
+            expect(userFromNumericId?.source).toEqual(DataSource.DATA_SOURCE_2);
+            expect(typeof userFromNumericId?.id).toBe('number');
         });
     });
 });