private function isIdentityValid(SaleInterface $cart)
    {
        return 0 < strlen($cart->getEmail())
            && 0 < strlen($cart->getGender())
            && 0 < strlen($cart->getFirstName())
            && 0 < strlen($cart->getLastName());
    }
private function isIdentityValid(SaleInterface $cart)
    {
        return 0 < strlen($cart->getEmail())
            && 0 < strlen($cart->getGender())
            && 0 < strlen($cart->getFirstName())
            && 0 < strlen($cart->getLastName());
    }
Returns whether the sale identity fields are valid.

@param SaleInterface $cart

@return bool