__version_info__ = (0, 1, 1)
__version__ = '.'.join(map(str, __version_info__))

__version_info__ = (0, 1, 1, 'a1')
__version__ = '.'.join(map(str, __version_info__[:3]))
if len(__version_info__) == 4:
    __version__ += __version_info__[-1]

Allow alpha versions in the versioning string