How to Implement an LFU Cache in Python

class LFUCache:
    def __init__(self, capacity: int):
        self.capacity = capacity
        self.data = {}
        self.freq = {}
        self.min_freq = 0

    def get(self, key: int) -> int:
        if key not in self.data:
            return -1
        self._increment_freq(key)
        return self.data[key]

    def put(self, key: int, value: int) -> None:
        if self.capacity <= 0:
            return
        if key in self.data:
            self.data[key] = value
            self._increment_freq(key)
            return
        if len(self.data) >= self.capacity:
            self._evict()
        self.data[key] = value
        self.freq[key] = 1
        self.min_freq = 1

    def _increment_freq(self, key: int) -> None:
        self.freq[key] += 1
        if self.freq[key] == 2:
            self.min_freq = 2

    def _evict(self) -> None:
        lfu_key = None
        lfu_freq = float('inf')
        for k, f in self.freq.items():
            if f < lfu_freq:
                lfu_freq = f
                lfu_key = k
        if lfu_key is not None:
            del self.data[lfu_key]
            del self.freq[lfu_key]
            if self.freq:
                self.min_freq = min(self.freq.values())


if __name__ == "__main__":
    cache = LFUCache(2)
    cache.put(1, 10)
    cache.put(2, 20)
    print(cache.get(1))
    cache.put(3, 30)
    print(cache.get(2))
    print(cache.get(3))