humps.decamelize('aB') got 'ab'，expect 'a_b‘ about humps

[Hultner]

I came here to report the same problem. This doesn't just happen with "aB" but any short. I have a few examples where round-tripping a string behaves unexpectedly.

# Inconsistent behaviour
>>> humps.camelize("ab")
'ab'
>>> humps.camelize("a_b")
'a_b'
>>> humps.camelize("a_be")
'a_be'
>>> humps.camelize("a_best")
'a_best'
>>> humps.camelize("ar_best")
'arBest'
# Incorrect roundtrip
>>> humps.decamelize(humps.camelize("area_b"))
'areab'



# Correct
>>> humps.decamelize(humps.camelize("aa_bb"))
'aa_bb'
# Wrong
>>> humps.decamelize(humps.camelize("aa_b"))
'aab'
# Correct
>>> humps.decamelize(humps.camelize("a_b"))
'a_b'
>>> humps.decamelize(humps.camelize("a_bb"))
'a_bb'


# Frist is wrong, second correct
>>> humps.camelize("a_b")
'a_b'
>>> humps.camelize("aa_ab")
'aaAb'