now using chain instead of +

test/test_spaces/test_power_space.py

@@ -27,13 +27,13 @@ from numpy.testing import assert_, assert_equal, assert_almost_equal,\
 from nifty import PowerSpace, RGSpace, Space, LMSpace
 from types import NoneType
 from test.common import expand
-from itertools import product
+from itertools import product, chain
 
 
 HARMONIC_SPACES = [RGSpace((8,), harmonic=True), RGSpace((7,8), harmonic=True), RGSpace((5,5), harmonic=True), RGSpace((4,5,7), harmonic=True),
 LMSpace(6),LMSpace(9)]
 
-BINNINGS = product([None], [None, 3,4], [True, False]) + product([0.,1.3],[None],[False])
+BINNINGS = chain(product([None], [None, 3,4], [True, False]), product([0.,1.3],[None],[False]))
 
 
 #Try all sensible kinds of combinations of spaces, distributuion strategy and