def get_nameplate_completions(prefix):
    """
        Return a list of nameplate completions for the given prefix.

        This takes the most-recently-received set of active nameplates from
        the rendezvous server, finds the subset that start with the given
        prefix, and returns the result.  The result strings include the
        prefix and the terminating hyphen, in random order.

        This returns synchronously: it does not wait for a server response.
        If called before getting any response from the server, it will return
        an empty set.  If user input causes completion, it may be a good idea
        to kick off a new ``refresh_nameplates()`` too, in case the user is
        bouncing on the TAB key in the hopes of seeing their expected
        nameplate appear in the list eventually.

        :param str prefix: the nameplate as typed so far

        :return: a set of potential completions
        :rtype: set[str]
        """
