Create a readable version string from version_info tuple components.

def _make_version(major, minor, micro, releaselevel, serial):
    """Create a readable version string from version_info tuple components."""
    assert releaselevel in ['alpha', 'beta', 'candidate', 'final']
    version = "%d.%d" % (major, minor)
    if micro:
        version += ".%d" % (micro,)
    if releaselevel != 'final':
        short = {'alpha': 'a', 'beta': 'b', 'candidate': 'rc'}[releaselevel]
        version += "%s%d" % (short, serial)
    return version