public function getNamespaces()
	{
		$namespaces = $this->instance->getInstanceNamespaces();

		$usedNamespaces = array_reduce( $this->elements, function( $carry, $element ) use( $namespaces ) {

			foreach ( $element as $key => $entry )
			{
				$namespace = isset( $namespaces[ $entry['namespace'] ] ) ? $namespaces[ $entry['namespace'] ] : $entry['namespace'];
				if ( ! isset( $carry[ $namespace ] ) )
					$carry[ $namespace ] = 1;
			}

			return $carry;
		}, array() );

		return array_keys( $usedNamespaces );
	}