Converts several files to consumable types.

def convert_multiple_sources_to_consumable_types (self, project, prop_set, sources):
        """ Converts several files to consumable types.
        """
        if __debug__:
            from .targets import ProjectTarget

            assert isinstance(project, ProjectTarget)
            assert isinstance(prop_set, property_set.PropertySet)
            assert is_iterable_typed(sources, virtual_target.VirtualTarget)
        if not self.source_types_:
            return list(sources)

        acceptable_types = set()
        for t in self.source_types_:
            acceptable_types.update(type.all_derived(t))

        result = []
        for source in sources:
            if source.type() not in acceptable_types:
                transformed = construct_types(
                    project, None,self.source_types_, prop_set, [source])
                # construct_types returns [prop_set, [targets]]
                for t in transformed[1]:
                    if t.type() in self.source_types_:
                        result.append(t)
                if not transformed:
                    project.manager().logger().log(__name__, "  failed to convert ", source)
            else:
                result.append(source)

        result = sequence.unique(result, stable=True)
        return result