finds hosts that postively match a particular pattern.  Does not
        take into account negative matches.

def __get_hosts(self, pattern):
        """ 
        finds hosts that postively match a particular pattern.  Does not
        take into account negative matches.
        """

        (name, enumeration_details) = self._enumeration_info(pattern)
        hpat = self._hosts_in_unenumerated_pattern(name)
        hpat = sorted(hpat, key=lambda x: x.name)

        return set(self._apply_ranges(pattern, hpat))