class Friend(models.Model): 
  from = ForeignKey('User', related_name='friends_of_me')
  to = ForeignKey('User', related_name='my_friends')


def first_degree(user): 
  return user.my_friends_set.all()

def second_degree(user): 
  # Totally bogus syntax below: 
  return user.my_friends_set.my_friends_set.all()