In Rust, a unit struct is a type of struct that doesn't have any fields. It is essentially a "marker" or "tag" type and is represented by an empty pair of curly braces (struct Name;).

Unit structs are particularly useful in scenarios where you need to define types without associated data. Here's an example:

pub struct Database;

In this challenge, you'll implement a unit struct named Logger. The struct will serve as a type marker that enables certain logging functionality via a method log_message. You'll also implement a log_message function that prints a message to the console using the unit struct Logger as a marker. The goal is to familiarize yourself with unit structs and their usage as markers.

1. Define a unit struct named Logger.

2. Implement a Logger::log_message method that:

   • Takes a &str message as input.
   • Prints the message to the console in the format: [LOG]: {message}.

3. Use the unit struct Logger to call this method.

Logger::log_message("This is a test log.");
// Output: [LOG]: This is a test log.