def _py2vim_scalar(value, null, true, false):
    """Return the given Python scalar translated to a Vim value.

    None, True, and False are returned as the (Vim) sentinel values 'null',
    'true', and 'false', respectively; anything else is returned untouched.
    """
    if value is None:
        return null
    if value is True:
        return true
    if value is False:
        return false
    return value