How to use the tzlocal.utils function in tzlocal

def test_assert_tz_offset(self):
        # The local zone should be the local zone:
        local = tzlocal.get_localzone()
        tzlocal.utils.assert_tz_offset(local)

        # Get a non local zone. Let's use Chatham, population 600.
        other = pytz.timezone('Pacific/Chatham')
        with self.assertRaises(ValueError):
            tzlocal.utils.assert_tz_offset(other)

def test_assert_tz_offset(self):
        # The local zone should be the local zone:
        local = tzlocal.get_localzone()
        tzlocal.utils.assert_tz_offset(local)

        # Get a non local zone. Let's use Chatham, population 600.
        other = pytz.timezone('Pacific/Chatham')
        with self.assertRaises(ValueError):
            tzlocal.utils.assert_tz_offset(other)

if not etctz:
                    # Empty file, skip
                    continue
                for etctz in data.decode().splitlines():
                    # Get rid of host definitions and comments:
                    if ' ' in etctz:
                        etctz, dummy = etctz.split(' ', 1)
                    if '#' in etctz:
                        etctz, dummy = etctz.split('#', 1)
                    if not etctz:
                        continue
                    tz = pytz.timezone(etctz.replace(' ', '_'))
                    if _root == '/':
                        # We are using a file in etc to name the timezone.
                        # Verify that the timezone specified there is actually used:
                        utils.assert_tz_offset(tz)
                    return tz

        except IOError:
            # File doesn't exist or is a directory
            continue

    # CentOS has a ZONE setting in /etc/sysconfig/clock,
    # OpenSUSE has a TIMEZONE setting in /etc/sysconfig/clock and
    # Gentoo has a TIMEZONE setting in /etc/conf.d/clock
    # We look through these files for a timezone:

    zone_re = re.compile(r'\s*ZONE\s*=\s*\"')
    timezone_re = re.compile(r'\s*TIMEZONE\s*=\s*\"')
    end_re = re.compile('\"')

    for filename in ('etc/sysconfig/clock', 'etc/conf.d/clock'):

if not etctz:
                    # Empty file, skip
                    continue
                for etctz in data.decode().splitlines():
                    # Get rid of host definitions and comments:
                    if ' ' in etctz:
                        etctz, dummy = etctz.split(' ', 1)
                    if '#' in etctz:
                        etctz, dummy = etctz.split('#', 1)
                    if not etctz:
                        continue
                    tz = pytz.timezone(etctz.replace(' ', '_'))
                    if _root == '/':
                        # We are using a file in etc to name the timezone.
                        # Verify that the timezone specified there is actually used:
                        utils.assert_tz_offset(tz)
                    return tz

        except IOError:
            # File doesn't exist or is a directory
            continue

    # CentOS has a ZONE setting in /etc/sysconfig/clock,
    # OpenSUSE has a TIMEZONE setting in /etc/sysconfig/clock and
    # Gentoo has a TIMEZONE setting in /etc/conf.d/clock
    # We look through these files for a timezone:

    zone_re = re.compile(r'\s*ZONE\s*=\s*\"')
    timezone_re = re.compile(r'\s*TIMEZONE\s*=\s*\"')
    end_re = re.compile('\"')

    for filename in ('etc/sysconfig/clock', 'etc/conf.d/clock'):

def get_localzone():
    """Returns the zoneinfo-based tzinfo object that matches the Windows-configured timezone."""
    global _cache_tz
    if _cache_tz is None:
        _cache_tz = pytz.timezone(get_localzone_name())

    utils.assert_tz_offset(_cache_tz)
    return _cache_tz

def reload_localzone():
    """Reload the cached localzone. You need to call this if the timezone has changed."""
    global _cache_tz
    _cache_tz = pytz.timezone(get_localzone_name())
    utils.assert_tz_offset(_cache_tz)
    return _cache_tz

# Look for the ZONE= setting.
                match = zone_re.match(line)
                if match is None:
                    # No ZONE= setting. Look for the TIMEZONE= setting.
                    match = timezone_re.match(line)
                if match is not None:
                    # Some setting existed
                    line = line[match.end():]
                    etctz = line[:end_re.search(line).start()]

                    # We found a timezone
                    tz = pytz.timezone(etctz.replace(' ', '_'))
                    if _root == '/':
                        # We are using a file in etc to name the timezone.
                        # Verify that the timezone specified there is actually used:
                        utils.assert_tz_offset(tz)
                    return tz

        except IOError:
            # File doesn't exist or is a directory
            continue

    # systemd distributions use symlinks that include the zone name,
    # see manpage of localtime(5) and timedatectl(1)
    tzpath = os.path.join(_root, 'etc/localtime')
    if os.path.exists(tzpath) and os.path.islink(tzpath):
        tzpath = os.path.realpath(tzpath)
        start = tzpath.find("/")+1
        while start != 0:
            tzpath = tzpath[start:]
            try:
                return pytz.timezone(tzpath)

# Look for the ZONE= setting.
                match = zone_re.match(line)
                if match is None:
                    # No ZONE= setting. Look for the TIMEZONE= setting.
                    match = timezone_re.match(line)
                if match is not None:
                    # Some setting existed
                    line = line[match.end():]
                    etctz = line[:end_re.search(line).start()]

                    # We found a timezone
                    tz = pytz.timezone(etctz.replace(' ', '_'))
                    if _root == '/':
                        # We are using a file in etc to name the timezone.
                        # Verify that the timezone specified there is actually used:
                        utils.assert_tz_offset(tz)
                    return tz

        except IOError:
            # File doesn't exist or is a directory
            continue

    # systemd distributions use symlinks that include the zone name,
    # see manpage of localtime(5) and timedatectl(1)
    tzpath = os.path.join(_root, 'etc/localtime')
    if os.path.exists(tzpath) and os.path.islink(tzpath):
        tzpath = os.path.realpath(tzpath)
        start = tzpath.find("/")+1
        while start is not 0:
            tzpath = tzpath[start:]
            try:
                return pytz.timezone(tzpath)

def get_localzone():
    """Returns the zoneinfo-based tzinfo object that matches the Windows-configured timezone."""
    global _cache_tz
    if _cache_tz is None:
        _cache_tz = pytz.timezone(get_localzone_name())

    utils.assert_tz_offset(_cache_tz)
    return _cache_tz

def reload_localzone():
    """Reload the cached localzone. You need to call this if the timezone has changed."""
    global _cache_tz
    _cache_tz = pytz.timezone(get_localzone_name())
    utils.assert_tz_offset(_cache_tz)
    return _cache_tz