src/Rules/HexadecimalTrait.php
private function validateHexadecimal($value)
    {
        $isValid = filter_var(
            $value,
            FILTER_VALIDATE_REGEXP,
            array(
                "options" => array("regexp" => '`^[0-9A-Fa-f]+$`'),
            )
        );
        if ($isValid === false) {
            $this->throwInvalidArgumentMustBe("valid hexadecimal");
        }
    }
private function validateHexadecimal($value)
    {
        $isValid = filter_var(
            $value,
            FILTER_VALIDATE_REGEXP,
            array(
                "options" => array("regexp" => '`^[0-9A-Fa-f]+$`'),
            )
        );
        if ($isValid === false) {
            $this->throwInvalidArgumentMustBe("valid hexadecimal");
        }
    }
Allowed characters: 0-9, a-f, A-F

@param $value