docs: def get_effective_agent_id_with_proxy(proxy):
      """Given a Proxy, returns the Id of the effective Agent"""
      if is_authenticated_with_proxy(proxy):
          if proxy.has_effective_agent():
              return proxy.get_effective_agent_id()
          else:
              return proxy.get_authentication().get_agent_id()
      else:
          return Id(
              identifier='MC3GUE$T@MIT.EDU',
              namespace='authentication.Agent',
              authority='MIT-ODL')