问如何在两个Django类之间共享Python方法？

EN

class ProfileManager(models.Manager):
    def create_profile(self, user, member):
        # Set default age to 100 years old when profile is created.
        years_ago100 = datetime.datetime.now() - datetime.timedelta(days=101 * 365)
        age = calculate_age(years_ago100)       # <- Used here
        profile = self.create(user=user, person_dob=years_ago100, person_age=age)
        return

class Profile(models.Model):
    person_dob = models.DateField()
    person_age = models.IntegerField()

    objects = ProfileManager()

    def save(self, *args, **kwargs):
      # Update to real age when user edits profile for the first time.
      self.person_age = calculate_age(self.person_dob)    # <- Used here too
      super(Profile, self).save(*args, **kwargs)

def calculate_age(born):
    today = datetime.date.today()
    return (today.year - born.year - ((today.month, today.day) < (born.month, born.day)))

def calculate_age(born):
  ...

class ProfileManager(models.Manager):
  ...

class Profile(models.Model):
  ...