Camel Cards

Camel Cards is a simplified two-player card game. You are given two strings, hand1 and hand2, representing the players' four-card hands. Each card is labeled with a digit from 1 through 9, where 9 is highest.

Hand Types

From strongest to weakest:

1. Four of a kind: all four cards are equal, such as 9999.
2. Two pair: two cards of one value and two cards of another value, such as 2332.
3. Three of a kind: three equal cards and one different card, such as 9998.
4. One pair: two equal cards and two other distinct cards, such as 5233.
5. High card: all four cards are distinct, such as 2345.

Ordering Rules

• A stronger hand type always wins.
• If both hands have the same type, compare their cards from right to left, which is from most recently dealt to first dealt.
• Do not sort the cards. At the first differing position, the hand with the higher card wins.
• If all four cards are equal, the result is a tie.

Return "HAND_1" if hand1 wins, "HAND_2" if hand2 wins, or "TIE".

Design the hand-type evaluation so that more hand types can be added later.