convert UTC datetime in string to unix timestamp using python3

str_to_timestamp.py

import datetime
import dateutil.parser # pip install python-dateutil

s = '2019-05-15T01:23:54Z'
d = dateutil.parser.parse(s)
t = d.replace(tzinfo=datetime.timezone.utc).timestamp()

# s = '2019-05-15T01:23:54Z'
# d = datetime.datetime(2019, 5, 15, 1, 23, 54, tzinfo=tzutc())
# t = 1557883434.0