In Django Polls Tutorial: Getting In Choice question =models.ForeignKey (Question, on_delete=models.CASCADE) NameError: name 'Question' is not defined

Question

from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

Once i make migrations for polls erroe occur which is in Choice question =models.ForeignKey (Question, on_delete=models.CASCADE) NameError: name 'Question' is not defined