get certificate expiration time in days, python3.6

utils.py

from OpenSSL import SSL
import socket
import datetime
import sys


def get_domain_certificate_expiration_days(domain: str, port: int=443) -> int:
    cur_date = datetime.datetime.utcnow()
    cert_tested = 0

    try:
        context = SSL.Context(SSL.SSLv23_METHOD)
        sock = SSL.Connection(
            context, socket.socket(socket.AF_INET, socket.SOCK_STREAM))
        try:
            sock.connect((str(domain), int(port)))
            # sock.do_handshake()
            sock.send("\x00")  # Send empty to trigger response
            get_peer_cert = sock.get_peer_certificate()
            sock.close()
            get_not_after = get_peer_cert.get_notAfter().decode('utf-8')
            exp_date = datetime.datetime.strptime(
                get_not_after, '%Y%m%d%H%M%SZ')
            days_to_expire = int((exp_date - cur_date).days)
            cert_tested = cert_tested + 1
            chain = sock.get_peer_cert_chain()
            return days_to_expire
        except Exception as e:
            return str(e)
    except SSL.Error as e:
        return str(e)