protected function isNamespaceValid($namespaceIdentifier, $methodIdentifier)
    {
        if (array_key_exists($namespaceIdentifier, $this->namespaces)) {
            return true;
        }

        foreach ($this->ignoredNamespaceIdentifierPatterns as $namespaceIdentifierPattern) {
            if (preg_match($namespaceIdentifierPattern, $namespaceIdentifier) === 1) {
                return false;
            }
        }

        throw new Exception(sprintf('Error while rendering a ViewHelper
			The namespace of ViewHelper notation "<%1$s:%2$s.../>" could not be resolved.

			Possible reasons are:
			* you have a spelling error in the viewHelper namespace
			* you forgot to import the namespace using "{namespace %1$s=Some\Package\ViewHelpers}"
			* you\'re trying to use a non-fluid xml namespace, in which case you can use "{namespace %1$s}" to ignore this namespace for fluid rendering', $namespaceIdentifier, $methodIdentifier), 1402521855);
    }