def set_missing_host_key_policy(self, policy):
self._policy = policy<EOL>
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local L{HostKeys} objects.  The
default policy is to reject all unknown servers (using L{RejectPolicy}).
You may substitute L{AutoAddPolicy} or write your own policy class.

@param policy: the policy to use when receiving a host key from a
    previously-unknown server
@type policy: L{MissingHostKeyPolicy}