axis[key] does not work when key contains special characters #200
Description
Those messy string evaluations are getting in the way once more
>>> arr = ndtest(3)
>>> agg = arr.sum('a1:a2;a0:a1;a0,a2')
>>> agg
a a1:a2 a0:a1 a0,a2
3 1 2
>>> agg[agg.a['a1:a2']]
ValueError Traceback (most recent call last)
...
ValueError: a['a1':'a2'] is not a valid label for any axis
>>> agg['a1:a2']
3
>>> agg[X.a['a1:a2']]
3