def get_version(version=None):
    """Return a PEP 440-compliant version number from VERSION."""
    version = get_complete_version(version)

    # Now build the two parts of the version number:
    # main = X.Y[.Z]
    # sub = .devN - for pre-alpha releases
    #     | {a|b|rc}N - for alpha, beta, and rc releases

    main = get_main_version(version)
    return main


def get_main_version(version=None):
    """Return main version (X.Y[.Z]) from VERSION."""
    version = get_complete_version(version)
    return '.'.join(str(x) for x in version)


def get_complete_version(version=None):
    """
    Return a tuple of the django version. If version argument is non-empty,
    check for correctness of the tuple provided.
    """
    if version is None:
        from postomaat import VERSION as version
    else:
        assert len(version) == 3

    return version