>>> arr = ndtest((2, 3))
>>> arr.reindex('a', ['a1', 'a2']).reindex('b', ['b1', 'b2'])
a\b   b1   b2
 a1  4.0  5.0
 a2  nan  nan
>>> arr.reindex({'a': ['a1', 'a2'], 'b': ['b1', 'b2']})
KeyError: "axis 'a' not found in {{0}, {1}}"
>>> arr.reindex({'a': Axis(['a1', 'a2'], 'a'), 'b': Axis(['b1', 'b2'], 'b')})
a\b   b1   b2
 a1  4.0  5.0
 a2  nan  nan