examples/01-blog/Blog/Type/Scalar/UrlType.php
public function parseValue($value)
    {
        if (!is_string($value) || !filter_var($value, FILTER_VALIDATE_URL)) { // quite naive, but after all this is example
            throw new Error("Cannot represent value as URL: " . Utils::printSafe($value));
        }
        return $value;
    }
public function parseValue($value)
    {
        if (!is_string($value) || !filter_var($value, FILTER_VALIDATE_URL)) { // quite naive, but after all this is example
            throw new Error("Cannot represent value as URL: " . Utils::printSafe($value));
        }
        return $value;
    }
Parses an externally provided value (query variable) to use as an input

@param mixed $value
@return mixed
@throws Error