diff --git a/nifty5/domain_tuple.py b/nifty5/domain_tuple.py
index 287192d9fe8b7a7972877c20c23a514f8ea1fb13..64d5b53adc9e303cc8f3641355fde20ab10d9e5f 100644
--- a/nifty5/domain_tuple.py
+++ b/nifty5/domain_tuple.py
@@ -37,6 +37,7 @@ class DomainTuple(object):
     via the factory function :attr:`make`!
     """
     _tupleCache = {}
+    _scalarDomain = None
 
     def __init__(self, domain, _callingfrommake=False):
         if not _callingfrommake:
@@ -150,3 +151,9 @@ class DomainTuple(object):
         for i in self:
             res += "\n" + str(i)
         return res
+
+    @staticmethod
+    def scalar_domain():
+        if DomainTuple._scalarDomain is None:
+            DomainTuple._scalarDomain = DomainTuple.make(())
+        return DomainTuple._scalarDomain
diff --git a/nifty5/utilities.py b/nifty5/utilities.py
index e7e7d120049366701e94da3db255d560e41d82ce..2ae4364c3a6436c85e9fc7a079b682426707893e 100644
--- a/nifty5/utilities.py
+++ b/nifty5/utilities.py
@@ -33,8 +33,8 @@ __all__ = ["get_slice_list", "safe_cast", "parse_spaces", "infer_space",
            "my_product", "frozendict", "special_add_at"]
 
 
-def my_sum(terms):
-    return reduce(lambda x, y: x+y, terms)
+def my_sum(iterable):
+    return reduce(lambda x, y: x+y, iterable)
 
 
 def my_lincomb_simple(terms, factors):