new_contents: from abc import ABCMeta, abstractmethod
  from enum import Enum
  
  
  class Broadcast(metaclass=ABCMeta):
      """
      An interface for defining a broadcast protocol.
      The 'propose' and 'decide' methods need to be defined
      """
  
      class MessageType(Enum):
          SEND = 1
          ECHO = 2
          READY = 3
  
      def __init__(self, node_number, faulty_nodes):
          self.N = node_number
          self.f = faulty_nodes
  
      @abstractmethod
      def broadcast(self, message):
          pass
  
      @abstractmethod
      def broadcast_listener(self):
          pass
  
      @abstractmethod
      def deliver(self, sender, message):
          pass
  
subject: Add abstract Broadcast protocol class