How to use the mailchecker.mailer function in mailchecker

from django.db.models import ForeignKey
from mservice_model.models import ServiceModel
from .manager import ThreadManager, MessageManager
from . import mailer
from django.db.models.fields import (AutoField, CharField, TextField)
from mservice_model.options import ServiceOptions


class GmailAutoField(AutoField):
    def to_python(self, value):
        return value


class Thread(ServiceModel):
    _default_manager = ThreadManager
    _service_api = mailer.GmailApi("h")

    # _meta = ThreadOptions()
    class Meta(ServiceOptions):
        _service_fields = {
            'id': GmailAutoField(),
            'to': CharField(max_length=200),
            'number_of_messages': CharField(max_length=200),
        }

    def __init__(self, id=None, to=None, number_of_messages=None):
        self.id = id
        self.to = to
        self.number_of_messages = number_of_messages

    @property
    def messages(self):