How to use the exchangelib.fields.DateTimeField function in exchangelib

BooleanField('is_meeting', field_uri='IsMeeting'),
        BooleanField('is_recurring', field_uri='IsRecurring'),
        BooleanField('is_exception', field_uri='IsException'),
        BooleanField('is_reminder_set', field_uri='IsReminderSet'),
        BooleanField('is_private', field_uri='IsPrivate'),
    ]

    __slots__ = tuple(f.name for f in FIELDS)


class CalendarEvent(EWSElement):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/calendarevent"""
    ELEMENT_NAME = 'CalendarEvent'
    FIELDS = [
        DateTimeField('start', field_uri='StartTime'),
        DateTimeField('end', field_uri='EndTime'),
        FreeBusyStatusField('busy_type', field_uri='BusyType', is_required=True, default='Busy'),
        EWSElementField('details', field_uri='CalendarEventDetails', value_cls=CalendarEventDetails),
    ]

    __slots__ = tuple(f.name for f in FIELDS)


class WorkingPeriod(EWSElement):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/workingperiod"""
    ELEMENT_NAME = 'WorkingPeriod'
    FIELDS = [
        EnumListField('weekdays', field_uri='DayOfWeek', enum=WEEKDAY_NAMES, is_required=True),
        TimeField('start', field_uri='StartTimeInMinutes', is_required=True),
        TimeField('end', field_uri='EndTimeInMinutes', is_required=True),
    ]

"""
    ELEMENT_NAME = 'Item'

    LOCAL_FIELDS = [
        MimeContentField('mime_content', field_uri='item:MimeContent', is_read_only_after_send=True),
        EWSElementField('parent_folder_id', field_uri='item:ParentFolderId', value_cls=ParentFolderId,
                        is_read_only=True),
        CharField('item_class', field_uri='item:ItemClass', is_read_only=True),
        CharField('subject', field_uri='item:Subject'),
        ChoiceField('sensitivity', field_uri='item:Sensitivity', choices={
            Choice('Normal'), Choice('Personal'), Choice('Private'), Choice('Confidential')
        }, is_required=True, default='Normal'),
        TextField('text_body', field_uri='item:TextBody', is_read_only=True, supported_from=EXCHANGE_2013),
        BodyField('body', field_uri='item:Body'),  # Accepts and returns Body or HTMLBody instances
        AttachmentField('attachments', field_uri='item:Attachments'),  # ItemAttachment or FileAttachment
        DateTimeField('datetime_received', field_uri='item:DateTimeReceived', is_read_only=True),
        IntegerField('size', field_uri='item:Size', is_read_only=True),  # Item size in bytes
        CharListField('categories', field_uri='item:Categories'),
        ChoiceField('importance', field_uri='item:Importance', choices={
            Choice('Low'), Choice('Normal'), Choice('High')
        }, is_required=True, default='Normal'),
        TextField('in_reply_to', field_uri='item:InReplyTo'),
        BooleanField('is_submitted', field_uri='item:IsSubmitted', is_read_only=True),
        BooleanField('is_draft', field_uri='item:IsDraft', is_read_only=True),
        BooleanField('is_from_me', field_uri='item:IsFromMe', is_read_only=True),
        BooleanField('is_resend', field_uri='item:IsResend', is_read_only=True),
        BooleanField('is_unmodified', field_uri='item:IsUnmodified', is_read_only=True),
        MessageHeaderField('headers', field_uri='item:InternetMessageHeaders', is_read_only=True),
        DateTimeField('datetime_sent', field_uri='item:DateTimeSent', is_read_only=True),
        DateTimeField('datetime_created', field_uri='item:DateTimeCreated', is_read_only=True),
        # Placeholder for ResponseObjects
        DateTimeField('reminder_due_by', field_uri='item:ReminderDueBy', is_required_after_save=True,

]

    __slots__ = tuple(f.name for f in FIELDS)


class Occurrence(IdChangeKeyMixIn):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/occurrence"""
    ELEMENT_NAME = 'Occurrence'

    LOCAL_FIELDS = [
        # The modified start time of the item, as EWSDateTime
        DateTimeField('start', field_uri='t:Start'),
        # The modified end time of the item, as EWSDateTime
        DateTimeField('end', field_uri='t:End'),
        # The original start time of the item, as EWSDateTime
        DateTimeField('original_start', field_uri='t:OriginalStart'),
    ]
    FIELDS = IdChangeKeyMixIn.FIELDS + LOCAL_FIELDS

    __slots__ = tuple(f.name for f in LOCAL_FIELDS)


# Container elements:
# 'ModifiedOccurrences'
# 'DeletedOccurrences'


class FirstOccurrence(Occurrence):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/firstoccurrence"""
    ELEMENT_NAME = 'FirstOccurrence'
    __slots__ = tuple()

]

    __slots__ = tuple(f.name for f in FIELDS)


class Attendee(EWSElement):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/attendee"""
    ELEMENT_NAME = 'Attendee'

    RESPONSE_TYPES = {'Unknown', 'Organizer', 'Tentative', 'Accept', 'Decline', 'NoResponseReceived'}

    FIELDS = [
        MailboxField('mailbox', is_required=True),
        ChoiceField('response_type', field_uri='ResponseType', choices={Choice(c) for c in RESPONSE_TYPES},
                    default='Unknown'),
        DateTimeField('last_response_time', field_uri='LastResponseTime'),
    ]

    __slots__ = tuple(f.name for f in FIELDS)

    def __hash__(self):
        # TODO: maybe take 'response_type' and 'last_response_time' into account?
        return hash(self.mailbox)


class TimeZoneTransition(EWSElement):
    """Base class for StandardTime and DaylightTime classes"""
    FIELDS = [
        IntegerField('bias', field_uri='Bias', is_required=True),  # Offset from the default bias, in minutes
        TimeField('time', field_uri='Time', is_required=True),
        IntegerField('occurrence', field_uri='DayOrder', is_required=True),  # n'th occurrence of weekday in iso_month
        IntegerField('iso_month', field_uri='Month', is_required=True),

__slots__ = ('mailbox',)

    def clean(self, version=None):
        from .folders import PublicFoldersRoot
        super(DistinguishedFolderId, self).clean(version=version)
        if self.id == PublicFoldersRoot.DISTINGUISHED_FOLDER_ID:
            # Avoid "ErrorInvalidOperation: It is not valid to specify a mailbox with the public folder root" from EWS
            self.mailbox = None


class TimeWindow(EWSElement):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/timewindow"""
    ELEMENT_NAME = 'TimeWindow'
    FIELDS = [
        DateTimeField('start', field_uri='StartTime', is_required=True),
        DateTimeField('end', field_uri='EndTime', is_required=True),
    ]

    __slots__ = tuple(f.name for f in FIELDS)


class FreeBusyViewOptions(EWSElement):
    """MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/freebusyviewoptions"""
    ELEMENT_NAME = 'FreeBusyViewOptions'
    REQUESTED_VIEWS = {'MergedOnly', 'FreeBusy', 'FreeBusyMerged', 'Detailed', 'DetailedMerged'}
    FIELDS = [
        EWSElementField('time_window', value_cls=TimeWindow, is_required=True),
        # Interval value is in minutes
        IntegerField('merged_free_busy_interval', field_uri='MergedFreeBusyIntervalInMinutes', min=6, max=1440,
                     default=30, is_required=True),
        ChoiceField('requested_view', field_uri='RequestedView', choices={Choice(c) for c in REQUESTED_VIEWS},
                    is_required=True),  # Choice('None') is also valid, but only for responses

class BaseMeetingReplyItem(BaseItem):
    """Base class for meeting request reply items that share the same fields (Accept, TentativelyAccept, Decline)"""
    FIELDS = [
        CharField('item_class', field_uri='item:ItemClass', is_read_only=True),
        ChoiceField('sensitivity', field_uri='item:Sensitivity', choices={
            Choice('Normal'), Choice('Personal'), Choice('Private'), Choice('Confidential')
        }, is_required=True, default='Normal'),
        BodyField('body', field_uri='item:Body'),  # Accepts and returns Body or HTMLBody instances
        AttachmentField('attachments', field_uri='item:Attachments'),  # ItemAttachment or FileAttachment
        MessageHeaderField('headers', field_uri='item:InternetMessageHeaders', is_read_only=True),
    ] + Message.LOCAL_FIELDS[:6] + [
        ReferenceItemIdField('reference_item_id', field_uri='item:ReferenceItemId', value_cls=ReferenceItemId),
        MailboxField('received_by', field_uri='message:ReceivedBy', is_read_only=True),
        MailboxField('received_representing', field_uri='message:ReceivedRepresenting', is_read_only=True),
        DateTimeField('proposed_start', field_uri='meeting:ProposedStart', supported_from=EXCHANGE_2013),
        DateTimeField('proposed_end', field_uri='meeting:ProposedEnd', supported_from=EXCHANGE_2013),
    ]

    __slots__ = tuple(f.name for f in FIELDS)

    def send(self, message_disposition=SEND_AND_SAVE_COPY):
        if not self.account:
            raise ValueError('%s must have an account' % self.__class__.__name__)

        res = self.account.bulk_create(items=[self], folder=self.folder, message_disposition=message_disposition)

        for r_item in res:
            if isinstance(r_item, Exception):
                raise r_item
        return res

class BaseMeetingReplyItem(BaseItem):
    """Base class for meeting request reply items that share the same fields (Accept, TentativelyAccept, Decline)"""
    FIELDS = [
        CharField('item_class', field_uri='item:ItemClass', is_read_only=True),
        ChoiceField('sensitivity', field_uri='item:Sensitivity', choices={
            Choice('Normal'), Choice('Personal'), Choice('Private'), Choice('Confidential')
        }, is_required=True, default='Normal'),
        BodyField('body', field_uri='item:Body'),  # Accepts and returns Body or HTMLBody instances
        AttachmentField('attachments', field_uri='item:Attachments'),  # ItemAttachment or FileAttachment
        MessageHeaderField('headers', field_uri='item:InternetMessageHeaders', is_read_only=True),
    ] + Message.LOCAL_FIELDS[:6] + [
        ReferenceItemIdField('reference_item_id', field_uri='item:ReferenceItemId', value_cls=ReferenceItemId),
        MailboxField('received_by', field_uri='message:ReceivedBy', is_read_only=True),
        MailboxField('received_representing', field_uri='message:ReceivedRepresenting', is_read_only=True),
        DateTimeField('proposed_start', field_uri='meeting:ProposedStart', supported_from=EXCHANGE_2013),
        DateTimeField('proposed_end', field_uri='meeting:ProposedEnd', supported_from=EXCHANGE_2013),
    ]

    __slots__ = tuple(f.name for f in FIELDS)

    def send(self, message_disposition=SEND_AND_SAVE_COPY):
        if not self.account:
            raise ValueError('%s must have an account' % self.__class__.__name__)

        res = self.account.bulk_create(items=[self], folder=self.folder, message_disposition=message_disposition)

        for r_item in res:
            if isinstance(r_item, Exception):
                raise r_item
        return res

return TentativelyAcceptItem(
            account=self.account,
            reference_item_id=ReferenceItemId(id=self.id, changekey=self.changekey),
            **kwargs
        ).send()


@python_2_unicode_compatible
class CalendarItem(Item, AcceptDeclineMixIn):
    """
    MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/calendaritem
    """
    ELEMENT_NAME = 'CalendarItem'
    LOCAL_FIELDS = [
        TextField('uid', field_uri='calendar:UID', is_required_after_save=True, is_searchable=False),
        DateTimeField('start', field_uri='calendar:Start', is_required=True),
        DateTimeField('end', field_uri='calendar:End', is_required=True),
        DateTimeField('original_start', field_uri='calendar:OriginalStart', is_read_only=True),
        BooleanField('is_all_day', field_uri='calendar:IsAllDayEvent', is_required=True, default=False),
        FreeBusyStatusField('legacy_free_busy_status', field_uri='calendar:LegacyFreeBusyStatus', is_required=True,
                            default='Busy'),
        TextField('location', field_uri='calendar:Location'),
        TextField('when', field_uri='calendar:When'),
        BooleanField('is_meeting', field_uri='calendar:IsMeeting', is_read_only=True),
        BooleanField('is_cancelled', field_uri='calendar:IsCancelled', is_read_only=True),
        BooleanField('is_recurring', field_uri='calendar:IsRecurring', is_read_only=True),
        BooleanField('meeting_request_was_sent', field_uri='calendar:MeetingRequestWasSent', is_read_only=True),
        BooleanField('is_response_requested', field_uri='calendar:IsResponseRequested', default=None,
                     is_required_after_save=True, is_searchable=False),
        ChoiceField('type', field_uri='calendar:CalendarItemType', choices={Choice(c) for c in CALENDAR_ITEM_CHOICES},
                    is_read_only=True),
        ChoiceField('my_response_type', field_uri='calendar:MyResponseType', choices={

]

    __slots__ = tuple(f.name for f in FIELDS)


class Attachment(EWSElement):
    """Base class for FileAttachment and ItemAttachment
    """
    FIELDS = [
        EWSElementField('attachment_id', value_cls=AttachmentId),
        TextField('name', field_uri='Name'),
        TextField('content_type', field_uri='ContentType'),
        TextField('content_id', field_uri='ContentId'),
        URIField('content_location', field_uri='ContentLocation'),
        IntegerField('size', field_uri='Size', is_read_only=True),  # Attachment size in bytes
        DateTimeField('last_modified_time', field_uri='LastModifiedTime'),
        BooleanField('is_inline', field_uri='IsInline'),
    ]

    __slots__ = tuple(f.name for f in FIELDS) + ('parent_item',)

    def __init__(self, **kwargs):
        self.parent_item = kwargs.pop('parent_item', None)
        super(Attachment, self).__init__(**kwargs)

    def clean(self, version=None):
        from .items import Item
        if self.parent_item is not None and not isinstance(self.parent_item, Item):
            raise ValueError("'parent_item' value %r must be an Item instance" % self.parent_item)
        # pylint: disable=access-member-before-definition
        if self.content_type is None and self.name is not None:
            self.content_type = mimetypes.guess_type(self.name)[0] or 'application/octet-stream'

IntegerField('size', field_uri='item:Size', is_read_only=True),  # Item size in bytes
        CharListField('categories', field_uri='item:Categories'),
        ChoiceField('importance', field_uri='item:Importance', choices={
            Choice('Low'), Choice('Normal'), Choice('High')
        }, is_required=True, default='Normal'),
        TextField('in_reply_to', field_uri='item:InReplyTo'),
        BooleanField('is_submitted', field_uri='item:IsSubmitted', is_read_only=True),
        BooleanField('is_draft', field_uri='item:IsDraft', is_read_only=True),
        BooleanField('is_from_me', field_uri='item:IsFromMe', is_read_only=True),
        BooleanField('is_resend', field_uri='item:IsResend', is_read_only=True),
        BooleanField('is_unmodified', field_uri='item:IsUnmodified', is_read_only=True),
        MessageHeaderField('headers', field_uri='item:InternetMessageHeaders', is_read_only=True),
        DateTimeField('datetime_sent', field_uri='item:DateTimeSent', is_read_only=True),
        DateTimeField('datetime_created', field_uri='item:DateTimeCreated', is_read_only=True),
        # Placeholder for ResponseObjects
        DateTimeField('reminder_due_by', field_uri='item:ReminderDueBy', is_required_after_save=True,
                      is_searchable=False),
        BooleanField('reminder_is_set', field_uri='item:ReminderIsSet', is_required=True, default=False),
        IntegerField('reminder_minutes_before_start', field_uri='item:ReminderMinutesBeforeStart',
                     is_required_after_save=True, min=0, default=0),
        CharField('display_cc', field_uri='item:DisplayCc', is_read_only=True),
        CharField('display_to', field_uri='item:DisplayTo', is_read_only=True),
        BooleanField('has_attachments', field_uri='item:HasAttachments', is_read_only=True),
        # ExtendedProperty fields go here
        CultureField('culture', field_uri='item:Culture', is_required_after_save=True, is_searchable=False),
        EffectiveRightsField('effective_rights', field_uri='item:EffectiveRights', is_read_only=True),
        CharField('last_modified_name', field_uri='item:LastModifiedName', is_read_only=True),
        DateTimeField('last_modified_time', field_uri='item:LastModifiedTime', is_read_only=True),
        BooleanField('is_associated', field_uri='item:IsAssociated', is_read_only=True, supported_from=EXCHANGE_2010),
        URIField('web_client_read_form_query_string', field_uri='item:WebClientReadFormQueryString',
                 is_read_only=True, supported_from=EXCHANGE_2010),
        URIField('web_client_edit_form_query_string', field_uri='item:WebClientEditFormQueryString',