How can I write a method within a Django model to retrieve related objects?

class Foo(models.Model):
     name = models.CharField()

class Bar(models.Model):
     title = models.CharField()
     Foo= models.ForeignKey('myapp.Foo')

class Foo(models.Model):
     name = models.CharField()
     def returnBars(self):
         ????

some_foo.bar_set.all()

class Foo(models.Model):
     name = models.CharField()

class Bar(models.Model):
     title = models.CharField()
     foo = models.ForeignKey(Foo, related_name='bars')

...

some_foo.bars.all()