Show dropped files

def show_dropped(self):
        """ Show dropped files """
        ctx = _find_context(self.broker)
        if ctx and ctx.all_files:
            ds = self.broker.get_by_type(datasource)
            vals = []
            for v in ds.values():
                if isinstance(v, list):
                    vals.extend(d.path for d in v)
                else:
                    vals.append(v.path)
            dropped = set(ctx.all_files) - set(vals)
            pprint("Dropped Files:", stream=self.stream)
            pprint(dropped, indent=4, stream=self.stream)