dswitch.py

class Switch:
    def __init__(self, nodes, q, node_id):
        self.proposer = Proposer(nodes, q, node_id)
    @endpoint
    def write(self, value, due):
        def change(previous):
            return value if previous == None else previous
        def query(current):
            if current == value:
                return current
            raise Conflict(current)
        return self.proposer.change_query(change, query, due)
    @endpoint
    def read(self, due):
        def change(previous):
            return previous
        def query(current):
            return current
        return self.proposer.change_query(change, query, due)