snowflake identifier generator implementation by python

snowflake.py

from time import time_ns
from threading import Lock

class SnowflakeGenerator:
        def __init__(self, instance_id, epoch=-1):
            self.instance_id = (instance_id&1023)<<12
            self.epoch = (time_ns()//1000 & 2199023255551) if epoch == -1 else epoch
            self.seq = 0
            self.last_timestamp = 0
            self.lock = Lock()

        def __call__(self):
            with self.lock:
                ts = (time_ns()//1000 & 2199023255551)<<22
                if ts == self.last_timestamp:
                    self.seq = (self.seq+1)&4095
                    if self.seq == 0:
                        ts = self.wait_for_next_millis()
                else:
                    self.seq == 0
                self.last_timestamp = ts
                return ts + self.instance_id + self.seq

        def wait_for_next_millis(self):
            while (t := (time_ns()//1000 & 2199023255551)<<22) == self.last_timestamp:
                pass
            return t