How to use the mailchecker.options.GmailOptions function in mailchecker

model_name = 'thread'
    verbose_name = 'thread'
    verbose_name_raw = 'thread'
    verbose_name_plural = 'threads'
    object_name = 'thread'
    default_related_name = None

    _gmail_pk_field = 'id'
    _gmail_fields = {
        'id': GmailAutoField(),
        'to': CharField(max_length=200),
        'number_of_messages': CharField(max_length=200),
    }


class MessageOptions(GmailOptions):
    app_label = 'mailchecker'
    model_name = 'message'
    verbose_name = 'message'
    verbose_name_raw = 'message'
    verbose_name_plural = 'messages'
    object_name = 'message'
    default_related_name = None

    _gmail_pk_field = 'id'
    _gmail_fields = {
        'id': GmailAutoField(),
        'receiver': CharField(max_length=200),
        'sender': CharField(max_length=200),
        'snippet': CharField(max_length=200),
        'body': TextField(),
    }

field for field_name, field in
            sorted(list(self._gmail_fields.items()) +
                   list(self._gmail_other_fields.items()))
        )

    def get_field(self, field_name):
        try:
            return self._gmail_fields[field_name]
        except KeyError:
            try:
                return self._gmail_other_fields[field_name]
            except KeyError:
                raise FieldDoesNotExist()


class ThreadOptions(GmailOptions):
    auto_created = False
    app_label = 'mailchecker'
    model_name = 'thread'
    verbose_name = 'thread'
    verbose_name_raw = 'thread'
    verbose_name_plural = 'threads'
    object_name = 'thread'
    default_related_name = None

    _gmail_pk_field = 'id'
    _gmail_fields = {
        'id': GmailAutoField(),
        'to': CharField(max_length=200),
        'number_of_messages': CharField(max_length=200),
    }