Bloom filter by python3

bloomfilter.py

import math
from hashlib import blake2b


class BloomFilter:
    def __init__(self, elements_count: int, *, error_rate: float = 0.0001) -> None:
        byte_count = 1 + int(
            -(math.log(error_rate) / math.log(2) ** 2) * elements_count // 8
        )
        digest_size = int(math.log2(elements_count)) + (elements_count % 2)
        self.bucket = bytearray(byte_count)
        self.hash_functions = [
            (lambda salt: (lambda x: (
                int.from_bytes(
                    blake2b(x, digest_size=digest_size, salt=salt).digest(), "big",
                )
                % (byte_count * 8)
            )))(salt)
            for salt in [
                i.to_bytes(1, "big")
                for i in range(int(-math.log(error_rate) // math.log(2)) + 1)
            ]
        ]

    def add(self, value: bytes) -> None:
        hashs = [hash_fn(value) for hash_fn in self.hash_functions]
        for num in hashs:
            self.bucket[num // 8] |= 2 ** (num % 8)

    def exists(self, value: bytes) -> bool:
        hashs = [hash_fn(value) for hash_fn in self.hash_functions]
        for num in hashs:
            if not self.bucket[num // 8] & (2 ** (num % 8)):
                return False
        return True