diff --git a/README.md b/README.md
index e78b129..45b73ae 100644
--- a/README.md
+++ b/README.md
@@ -35,11 +35,17 @@ Then publish the assets from your provider :
 php artisan vendor:publish
 ```
 
-Finally add your API key in the .env :
+Finally get your API key :
 
 ```bash
-BMAIL_API_KEY=your_key
-BMAIL_API_URL=the_api_url
+Connect to https://bluescale.email, go to the Templates tab, click on the API button and copy your API key.
+```
+
+And add it in your .env, along with the API URL :
+
+```bash
+BMAIL_API_KEY=your_api_key
+BMAIL_API_URL=https://bluescale.email/api/project/template/send
 ```
 
 ## Usage
diff --git a/composer.json b/composer.json
index 8680ee4..b1eed97 100644
--- a/composer.json
+++ b/composer.json
@@ -32,6 +32,8 @@
         }
     },
     "require": {
-        "guzzlehttp/guzzle": "^6.5"
-    }
+        "guzzlehttp/guzzle": "^6.5",
+        "php": "^7.2"
+    },
+    "prefer-stable": true
 }
diff --git a/src/BMailApi.php b/src/BMailApi.php
index 1a681d4..51519dd 100644
--- a/src/BMailApi.php
+++ b/src/BMailApi.php
@@ -1,10 +1,9 @@
 <?php
 
-
 namespace BMail;
 
 use GuzzleHttp\Client;
-
+use Psr\Http\Message\StreamInterface;
 
 class BMailApi
 {
@@ -25,7 +24,7 @@ class BMailApi
      * @return \Psr\Http\Message\StreamInterface
      * @throws BMailException
      */
-    public function send($template)
+    public function send($template): StreamInterface
     {
         $url = config('bmail.api_url');
 
diff --git a/src/BMailException.php b/src/BMailException.php
index 00ce41b..dc915b1 100644
--- a/src/BMailException.php
+++ b/src/BMailException.php
@@ -1,7 +1,5 @@
 <?php
 
-
 namespace BMail;
 
-
 class BMailException extends \Exception {}
diff --git a/src/BMailServiceProvider.php b/src/BMailServiceProvider.php
index daed5ff..ffaae48 100644
--- a/src/BMailServiceProvider.php
+++ b/src/BMailServiceProvider.php
@@ -1,11 +1,9 @@
 <?php
 
-
 namespace BMail;
 
 use Illuminate\Support\ServiceProvider;
 
-
 class BMailServiceProvider extends ServiceProvider
 {
     /**
diff --git a/src/BMailTemplate.php b/src/BMailTemplate.php
index 44a26ab..9ca6542 100644
--- a/src/BMailTemplate.php
+++ b/src/BMailTemplate.php
@@ -1,6 +1,5 @@
 <?php
 
-
 namespace BMail;
 
 class BMailTemplate implements \JsonSerializable
@@ -153,7 +152,7 @@ class BMailTemplate implements \JsonSerializable
      *
      * @return array
      */
-    public function toArray()
+    public function toArray(): array
     {
         return [
             'template' => $this->template,
@@ -168,5 +167,4 @@ class BMailTemplate implements \JsonSerializable
     {
         return $this->toArray();
     }
-
 }
diff --git a/src/Broadcasting/BMailChannel.php b/src/Broadcasting/BMailChannel.php
index a2dfb09..b92ee3c 100644
--- a/src/Broadcasting/BMailChannel.php
+++ b/src/Broadcasting/BMailChannel.php
@@ -1,14 +1,19 @@
 <?php
 
-
 namespace BMail;
 
 use Illuminate\Notifications\Notification;
-
+use Psr\Http\Message\StreamInterface;
 
 class BMailChannel
 {
-    public function send($notifiable, Notification $notification)
+    /**
+     * @param $notifiable
+     * @param Notification $notification
+     * @return \Psr\Http\Message\StreamInterface
+     * @throws BMailException
+     */
+    public function send($notifiable, Notification $notification): StreamInterface
     {
         $template = $notification->toTemplate($notifiable);