Use function getConcordanceTarget() over direct array access

src/MDConcCurrencies.php

@@ -9,9 +9,9 @@ declare(strict_types = 1);
 /**
  * Provides lists for categorizing spelled out currencies.
  */
-final class MDConcCurrencies {
+final class MDConcCurrencies implements MDImporterConcordanceListInterface {
 
-    const CURRENCIES_LIST = [
+    private const CURRENCIES_LIST = [
         "^" => "",
         "-" => "",
         "x" => "",
@@ -48,4 +48,20 @@ final class MDConcCurrencies {
         "US dollar" => "us-USD",
     ];
 
+    /**
+     * Require a function for getting the concordance target.
+     *
+     * @param string $input Input string.
+     *
+     * @return string
+     */
+    public static function getConcordanceTarget(string $input):string {
+
+        if (!isset(self::CURRENCIES_LIST[$input])) {
+            throw new MDImporterMissingConcordance("Unknown currency: " . $input);
+        }
+
+        return self::CURRENCIES_LIST[$input];
+
+    }
 }