Add detailed return annotation for compile method

Author: theodorejb

src/Compiler.php

@@ -65,7 +65,7 @@ public static function composePHPRender(Context $context, string $code): string
             use {$safeStringClass};
             use {$helperOptions};
             use {$runtimeContext};
-            return function (\$in = null, array \$options = []) {
+            return function (mixed \$in = null, array \$options = []) {
                 \$helpers = $helpers;
                 \$partials = [$partials];
                 \$cx = new RuntimeContext(

src/Handlebars.php

@@ -9,6 +9,7 @@ final class Handlebars
 
     /**
      * Compiles a template so it can be executed immediately.
+     * @return \Closure(mixed=, array=):string
      */
     public static function compile(string $template, Options $options = new Options()): \Closure
     {