Fix bad import.

pymatgen/io/abinit/flows.py

@@ -22,7 +22,7 @@
 from tabulate import tabulate
 from pydispatch import dispatcher
 from collections import OrderedDict
-from monty.collections import as_set, dict2namedtuple
+from monty.collections import dict2namedtuple
 from monty.string import list_strings, is_string, make_banner
 from monty.operator import operator_from_str
 from monty.io import FileLock