code: def actualize_source_type (self, sources, prop_set):
          
          assert is_iterable_typed(sources, VirtualTarget)
          assert isinstance(prop_set, property_set.PropertySet)
          result = []
          for i in sources:
              scanner = None
  
  # FIXME: what's this?
  #            if isinstance (i, str):
  #                i = self.manager_.get_object (i)
  
              if i.type ():
                  scanner = b2.build.type.get_scanner (i.type (), prop_set)
  
              r = i.actualize (scanner)
              result.append (r)
  
          return result
docs: Helper for 'actualize_sources'.
              For each passed source, actualizes it with the appropriate scanner.
              Returns the actualized virtual targets.