当然是通过返回对象本身以便进行后续调用。最常见的就是链式调用. Returning self from a method simply means that your method returns a reference to the instance object on which it was called. This can sometimes be seen in use with object oriented APIs that are designed as a fluent interface that encourages method cascading. 例子如下：
class Pig(object):
def __init__(self):
self.ball = 0
def eat(self):
self.ball += 1
return self
f = Pig()
f.eat().eat().eat()
print(f.myattr)
