public function getMethod($nameOrMethod): PhpMethod {
		if ($nameOrMethod instanceof PhpMethod) {
			$nameOrMethod = $nameOrMethod->getName();
		}

		if (!$this->methods->has($nameOrMethod)) {
			throw new \InvalidArgumentException(sprintf('The method "%s" does not exist.', $nameOrMethod));
		}

		return $this->methods->get($nameOrMethod);
	}