testbox = box.Box() testbox.put('b', 42) @testbox.pass_('b') def fn(a, b, c): return a + b + c fn(1, 2, 3) # (1) _? fn(1, 2) # (2) _? fn(a=1, b=2, c=3) # (3) _? fn(a=1, c=2) # (4) _?