def _start_end(**kwargs):  # {{{
    """
    Validate the position arguments. See DistLoad.__init_()

    Returns:
        Postition as a (start, end) tuple

    Examples:
        >>> _start_end(pos=(100, 200))
        (100, 200)
        >>> _start_end(start=100, end=200)
        (100, 200)
    """
    if "pos" in kwargs:
        p = kwargs["pos"]
        if not isinstance(p, tuple) and len(p) != 2:
            raise ValueError("'pos' should be a 2-tuple")
        pos = (round(float(kwargs["pos"][0])), round(float(kwargs["pos"][1])))
    elif "start" in kwargs and "end" in kwargs:
        pos = (round(float(kwargs["start"])), round(float(kwargs["end"])))
    else:
        raise KeyError("Neither 'pos' or 'start' and 'end' present")
    return pos