#==================== Current approach ====================

    @classmethod
    def from_partial(cls, **kwargs):
        assert 2 == sum(1 for name in ("left", "right", "center_x", "width") if name in kwargs), "x coordinates are overspecified or underspecified"
        if "width" in kwargs and "left" in kwargs:
            right = kwargs["width"] + kwargs["left"]
        elif "right" in kwargs and "width" in kwargs:
            left = kwargs["right"] - kwargs["width"]
        elif "center_x" in kwargs and "right" in kwargs:
            left = 2*kwargs["center_x"] - kwargs["right"]
        elif "center_x" in kwargs and "left" in kwargs:
            right = 2*kwargs["center_x"] - kwargs["left"]
        elif "center_x" in kwargs and "width" in kwargs:
            left = kwargs["center_x"] - kwargs["width"]/2
            right = kwargs["center_x"] + kwargs["width"]/2
        if "left" in kwargs: left = kwargs["left"]
        if "right" in kwargs: right = kwargs["right"]

        assert 2 == sum(1 for name in ("top", "bottom", "center_y", "height") if name in kwargs), "y coordinates are overspecified or underspecified"
        if "height" in kwargs and "top" in kwargs:
            bottom = kwargs["height"] + kwargs["top"]
        elif "bottom" in kwargs and "height" in kwargs:
            top = kwargs["bottom"] - kwargs["height"]
        elif "center_y" in kwargs and "bottom" in kwargs:
            top = 2*kwargs["center_y"] - kwargs["bottom"]
        elif "center_y" in kwargs and "top" in kwargs:
            bottom = 2*kwargs["center_y"] - kwargs["top"]
        elif "center_y" in kwargs and "height" in kwargs:
            top = kwargs["center_y"] - kwargs["height"]/2
            bottom = kwargs["center_y"] + kwargs["height"]/2
        if "top" in kwargs: top = kwargs["top"]
        if "bottom" in kwargs: bottom = kwargs["bottom"]
        return cls(left, top, right, bottom)

#==================== Namespacey approach ====================
    @classmethod
    def from_partial(cls, **kwargs):
        d = create_magical_namespace(kwargs)
        assert 2 == sum(1 for name in ("left", "right", "center_x", "width") if name in d), "x coordinates are overspecified or underspecified"
        if "width" in d and "left" in d:
            right = d.width + d.left
        elif "right" in d and "width" in d:
            left = d.right - d.width
        elif "center_x" in d and "right" in d:
            left = 2*d.center_x - d.right
        elif "center_x" in d and "left" in d:
            right = 2*d.center_x - d.left
        elif "center_x" in d and "width" in d:
            left = d.center_x - d.width/2
            right = d.center_x + d.width/2
        if "left" in d: left = d.left
        if "right" in d: right = d.right

        assert 2 == sum(1 for name in ("top", "bottom", "center_y", "height") if name in d), "y coordinates are overspecified or underspecified"
        if "height" in d and "top" in d:
            bottom = d.height + d.top
        elif "bottom" in d and "height" in d:
            top = d.bottom - d.height
        elif "center_y" in d and "bottom" in d:
            top = 2*d.center_y - d.bottom
        elif "center_y" in d and "top" in d:
            bottom = 2*d.center_y - d.top
        elif "center_y" in d and "height" in d:
            top = d.center_y - d.height/2
            bottom = d.center_y + d.height/2
        if "top" in d: top = d.top
        if "bottom" in d: bottom = d.bottom
        return cls(left, top, right, bottom)