diff --git a/public/index.php b/public/index.php
index d8e1d1f..3831ddd 100644
--- a/public/index.php
+++ b/public/index.php
@@ -1,3 +1,10 @@
 <?php
 
+/**
+ * The front controller for the QuickTopUp API.
+ *
+ * @package QuickTopUpAPI
+ */
+
+// Load the environment variables.
 require_once __DIR__.'/../src/bootstrap.php';
\ No newline at end of file
diff --git a/src/Api/ApiClient.php b/src/Api/ApiClient.php
index 51005d6..bc3e84a 100644
--- a/src/Api/ApiClient.php
+++ b/src/Api/ApiClient.php
@@ -2,8 +2,6 @@
 
 namespace QuickTopUpAPI\Api;
 
-use DateTime;
-use DateTimeZone;
 use GuzzleHttp\Client;
 use GuzzleHttp\Exception\GuzzleException;
 
@@ -76,10 +74,12 @@ public function sendRequest(
     string $endpoint,
     array $data = []
   ): mixed {
-    // Generate the timestamp in the specified format and ensure it's in GMT/UTC
+    // Generate the timestamp in GMT/UTC format
     $timestamp = gmdate('Y-m-d\TH:i:s');
     $authKey = $this->generateAuthHmac($timestamp, $this->apiSecurityKey);
-    $hashedPassword = $this->generateAuthHmac(hash('sha256', $this->apiPassword), $authKey);
+    $hashedPassword = $this->generateAuthHmac(
+      hash('sha256', $this->apiPassword), $authKey
+    );
 
     // Add authentication parameters to the request data.
     $data = array_merge([
@@ -106,12 +106,13 @@ public function sendRequest(
   /**
    * Generates an HMAC SHA256 hash using the API security key.
    *
-   * @param string $message The message to hash.
-   * @param string $secret The secret key for HMAC.
+   * @param  string  $message  The message to hash.
+   * @param  string  $secret   The secret key for HMAC.
+   *
    * @return string The base64-encoded HMAC hash.
    */
   private function generateAuthHmac($message, $secret): string {
-    return base64_encode(hash_hmac('sha256', $message, $secret, true));
+    return base64_encode(hash_hmac('sha256', $message, $secret, TRUE));
   }
 
 }
diff --git a/src/Model/Product.php b/src/Model/Product.php
index 72575aa..aa717f3 100644
--- a/src/Model/Product.php
+++ b/src/Model/Product.php
@@ -7,7 +7,10 @@
  *
  * @package QuickTopUpAPI\Model
  *
- * A simple product model.
+ * Note. This is a simple product model, in a real scenario it will be
+ * a database model.
+ *
+ * Not currently used, created to expand functionality.
  */
 class Product {