Use function getConcordanceTarget() over direct array access

src/MDConcLanguages.php

@@ -9,11 +9,27 @@ declare(strict_types = 1);
 /**
  * Provides lists for categorizing spelled out languages.
  */
-final class MDConcLanguages {
+final class MDConcLanguages implements MDImporterConcordanceListInterface {
 
-    const LANGUAGES_LIST = [
+    private const LANGUAGES_LIST = [
         'Deutsch' => 'de',
         'German' => 'de',
     ];
 
+    /**
+     * Require a function for getting the concordance target.
+     *
+     * @param string $input Input string.
+     *
+     * @return string
+     */
+    public static function getConcordanceTarget(string $input):string {
+
+        if (!isset(self::LANGUAGES_LIST[$input])) {
+            throw new MDImporterMissingConcordance("Unknown language type: " . $input);
+        }
+
+        return self::LANGUAGES_LIST[$input];
+
+    }
 }