Rust - Is it possible to test whether Enum variants are sequential without assigning each variant a value?

Is there a way to tell if Enum variants are directly sequential without assigning a value to each? For instance, I am trying to see if a poker hand is a straight and want to see if all five cards are in sequential value.

#[derive(PartialEq, PartialOrd, Eq, Hash, Copy, Clone, Debug)]
enum CardNumber {
    Two,
    Three,
    Four,
    Five,
    Six,
    Seven,
    Eight,
    Nine,
    Ten,
    Jack,
    Queen,
    King,
    Ace,
}

fn is_sequential(card1, card2) {
     card2 == card1 + 1 // pseudo code, function I'm looking for goes here.
}

use CardNumber::*;
let cards = [Ten, Jack, Queen, King, Ace];
let is_sequential: bool = cards
    .windows(2)
    .all(|(card1, card2)| is_sequential(card1, card2));

In order to compare whether variants are sequential, do I need to add a value to each variant, or is there another function that does this?