Python telegram send bulk messages to all contacts

tg_bulk_msg.py

from telethon.sync import TelegramClient
from telethon.tl.types import InputPeerUser
from telethon import functions
from time import sleep

api_id = 359***
api_hash = 'fe0b***'
with TelegramClient("moenk", api_id, api_hash) as client:
    contacts = client(functions.contacts.GetContactsRequest(hash=0))
    for u in contacts.users:
        sleep(2)
        print(u.username)
        client.send_message(InputPeerUser(u.id, u.access_hash), "Frohe Ostern! Urbi et orbi.")