docs: 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))