Python3 で Cloud Firestore のデータを削除 (Delete)

#! /usr/bin/python
#
import sys
import firebase_admin
from firebase_admin import credentials
from firebase_admin import firestore

# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
key_in = sys.argv[1]
#
print(key_in)
#
cred = credentials.ApplicationDefault()
firebase_admin.initialize_app(cred, {
  'projectId': 'my-project-2020-01-22',
})

db = firestore.client()
#
db.collection('cities').document(key_in).delete()
#
sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

export GOOGLE_APPLICATION_CREDENTIALS="***.json"
./firestore_delete.py t0924

$ python --version
Python 3.8.6