TASK: Remove local variable

* As we can use returns instead of local variable.
* This will make it easier to see the return value of the method.

src/Installer.php

@@ -42,9 +42,8 @@ class Installer extends LibraryInstaller
      */
     public function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
-        $isInstalled = parent::isInstalled($repo, $package);
-        if (!$isInstalled) {
-            return $isInstalled;
+        if (!parent::isInstalled($repo, $package)) {
+            return false;
         }
         $sourceStandards = $this->getSourceStandards($package);
         $destinationStandards = $this->getDestinationStandards($repo);
@@ -53,12 +52,11 @@ class Installer extends LibraryInstaller
             if (!$destinationStandards->hasStandard($sourceStandard)
                 || !$this->compareStandards($sourceStandard, $destinationStandards->getStandard($sourceStandard))
             ) {
-                $isInstalled = false;
-                break;
+                return false;
             }
         }
 
-        return $isInstalled;
+        return true;
     }
 
     /**