code: def validate_policy(topic, signer, routing_policy, nitpicky=False):
      
      if topic in routing_policy:
          # If so.. is the signer one of those permitted senders?
          if signer in routing_policy[topic]:
              # We are good.  The signer of this message is explicitly
              # whitelisted to send on this topic in our config policy.
              return True
          else:
              # We have a policy for this topic and $homeboy isn't on the list.
              _log.error("Authorization/routing_policy error.  "
                         "Topic %r.  Signer %r." % (topic, signer))
              return False
      else:
          # We don't have a policy for this topic.  How we react next for an
          # underspecified routing_policy is based on a configuration option.
  
          # Ideally, we are in nitpicky mode.  We leave it disabled while
          # standing up fedmsg across our environment so that we can build our
          # policy without having the whole thing come crashing down.
          if nitpicky:
              # We *are* in nitpicky mode.  We don't have an entry in the
              # routing_policy for the topic of this message.. and *nobody*
              # gets in without a pass.  That means that we fail the message.
              _log.error("Authorization/routing_policy underspecified.")
              return False
          else:
              # We are *not* in nitpicky mode.  We don't have an entry in the
              # routing_policy for the topic of this message.. but we don't
              # really care.
              _log.warning('No routing policy defined for "{t}" but routing_nitpicky is '
                           'False so the message is being treated as authorized.'.format(t=topic))
              return True
docs: Checks that the sender is allowed to emit messages for the given topic.
  
      Args:
          topic (str): The message topic the ``signer`` used when sending the message.
          signer (str): The Common Name of the certificate used to sign the message.
  
      Returns:
          bool: True if the policy defined in the settings allows the signer to send
              messages on ``topic``.