How to use the zulip.integrations.zephyr.zephyr_mirror_backend.States function in zulip

heading = "[-i %s]\n" % (notice.instance,)
        else:
            heading = ""
        zeph["content"] = heading + zeph["content"]

    zeph = decode_unicode_byte_strings(zeph)

    logger.info("Received a message on %s/%s from %s..." %
                (zephyr_class, notice.instance, notice.sender))
    if log is not None:
        log.write(json.dumps(zeph) + '\n')
        log.flush()

    if os.fork() == 0:
        global CURRENT_STATE
        CURRENT_STATE = States.ChildSending
        # Actually send the message in a child process, to avoid blocking.
        try:
            res = send_zulip(zeph)
            if res.get("result") != "success":
                logger.error("Error relaying zephyr:\n%s\n%s" % (zeph, res))
        except Exception:
            logger.exception("Error relaying zephyr:")
        finally:
            os._exit(0)

def die_gracefully(signal, frame):
    # type: (int, FrameType) -> None
    if CURRENT_STATE == States.ZulipToZephyr or CURRENT_STATE == States.ChildSending:
        # this is a child process, so we want os._exit (no clean-up necessary)
        os._exit(1)

    if CURRENT_STATE == States.ZephyrToZulip and not options.use_sessions:
        try:
            # zephyr=>zulip processes may have added subs, so run cancelSubs
            zephyr._z.cancelSubs()
        except IOError:
            # We don't care whether we failed to cancel subs properly, but we should log it
            logger.exception("")

    sys.exit(1)

options.forward_mail_zephyrs = subscribed_to_mail_messages()

    if options.session_path is None:
        options.session_path = "/var/tmp/%s" % (options.user,)

    if options.forward_from_zulip:
        child_pid = os.fork()  # type: Optional[int]
        if child_pid == 0:
            CURRENT_STATE = States.ZulipToZephyr
            # Run the zulip => zephyr mirror in the child
            configure_logger(logger, "zulip=>zephyr")
            zulip_to_zephyr(options)
            sys.exit(0)
    else:
        child_pid = None
    CURRENT_STATE = States.ZephyrToZulip

    import zephyr
    logger_name = "zephyr=>zulip"
    if options.shard is not None:
        logger_name += "(%s)" % (options.shard,)
    configure_logger(logger, logger_name)
    # Have the kernel reap children for when we fork off processes to send Zulips
    signal.signal(signal.SIGCHLD, signal.SIG_IGN)
    zephyr_to_zulip(options)

import subprocess
import optparse
import os
import datetime
import textwrap
import signal
import logging
import hashlib
import tempfile
import select

DEFAULT_SITE = "https://api.zulip.com"

class States(object):
    Startup, ZulipToZephyr, ZephyrToZulip, ChildSending = list(range(4))
CURRENT_STATE = States.Startup

logger = cast(logging.Logger, None)  # type: logging.Logger  # FIXME cast should not be needed?

def to_zulip_username(zephyr_username):
    # type: (str) -> str
    if "@" in zephyr_username:
        (user, realm) = zephyr_username.split("@")
    else:
        (user, realm) = (zephyr_username, "ATHENA.MIT.EDU")
    if realm.upper() == "ATHENA.MIT.EDU":
        # Hack to make ctl's fake username setup work :)
        if user.lower() == 'golem':
            user = 'ctl'
        return user.lower() + "@mit.edu"
    return user.lower() + "|" + realm.upper() + "@mit.edu"