example.py

def __init__(self):
    # initialize the successor chain
    self.chain1 = Dispenser50()
    self.chain2 = Dispenser20()
    self.chain3 = Dispenser10()

    # set the chain of responsibility
    # The Client may compose chains once or
    # the hadler can set them dynamically at
    # handle time
    self.chain1.set_successor(self.chain2)
    self.chain2.set_successor(self.chain3)