public function size($len)
    {
        $len = (int) $len;
        if (is_string($this->value)) {
            $message = ['%s {{does not have|has}} a string length of %s', $this->value, $len];
            $this->assert((strlen($this->value) === $len), $message);
        }

        if (is_int($this->value)) {
            $message = ['Integer %s {{does not have|has}} a size of %s', $this->value, $len];
            $this->assert(($this->value === $len), $message);
        }

        if (is_array($this->value)) {
            $message = ['Array {{does not have|has}} a size of %s', $len];
            $this->assert((count($this->value) === $len), $message);
        }

        return $this;
    }