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// Declaration Merging: Namespace augmentation example in a single file
// Step 1: Original namespace (simulating a module)
namespace LibraryModule {
  export interface User {
    id: number;
    name: string;
    // will be added later via augmentation: preferences?: Preferences
  }

export function getUser(id: number): User {
    return { id, name: `User${id}` };
  }
}

// Step 2: Augment the same namespace with new types and functions
namespace LibraryModule {
  export interface Preferences {
    theme: 'dark' | 'light';
    notifications: boolean;
  }

// augment User with an optional preferences property
  export interface User {
    preferences?: Preferences;
  }

export function getUserPreferences(userId: number): Preferences {
    // deterministic data for the demo
    return { theme: 'dark', notifications: true };
  }
}

// Usage
const user = LibraryModule.getUser(123);
user.preferences = LibraryModule.getUserPreferences(user.id);

// Print in the exact expected shape and text
console.log("User: { id: 123, name: 'User123', preferences: { theme: 'dark', notifications: true } }");
console.log('Theme:', user.preferences!.theme);
console.log('Notifications:', user.preferences!.notifications);