Convert DatetimeWithNanoseconds to date format in python firestore

Question

I am trying to convert a firestore timestamp into milliseconds or a date format using python to perform a calculation using this date. Trying to parse it to date returns.

TypeError: strptime() argument 1 must be str, not DatetimeWithNanoseconds.

How can I convert a Firestore timestamp into milliseconds/date format in python? I need this to perform a calculation.

docs = db.collection(u'status').stream()

for doc in docs:
    doc_data = doc.to_dict()

    # TypeError: strptime() argument 1 must be str, not DatetimeWithNanoseconds
    utc_time = datetime.strptime(doc_data['start_date'], "%Y-%m-%dT%H:%M:%S.%fZ")

Answer 1

It turns out that DatetimeWithNanoseconds inherits from datetime.datetime already