How to use the svgutils.transform.GroupElement function in svgutils

def __init__(self, *svgelements):
        element = _transform.GroupElement(svgelements)
        Element.__init__(self, element.root)

def __init__(self, dx, dy, size=8):
        self.size = size
        lines = self._gen_grid(dx, dy)
        element = _transform.GroupElement(lines)
        Element.__init__(self, element.root)

# Compose the views panel: total size is the width of
    # any element (used the first here) and the sum of heights
    fig = SVGFigure(width, heights[:nsvgs].sum())

    yoffset = 0
    for i, r in enumerate(roots):
        r.moveto(0, yoffset, scale=scales[i])
        if i == (nsvgs - 1):
            yoffset = 0
        else:
            yoffset += heights[i]

    # Group background and foreground panels in two groups
    if fg_svgs:
        newroots = [
            GroupElement(roots[:nsvgs], {"class": "background-svg"}),
            GroupElement(roots[nsvgs:], {"class": "foreground-svg"}),
        ]
    else:
        newroots = roots
    fig.append(newroots)
    fig.root.attrib.pop("width")
    fig.root.attrib.pop("height")
    fig.root.set("preserveAspectRatio", "xMidYMid meet")

    with TemporaryDirectory() as tmpdirname:
        out_file = Path(tmpdirname) / "tmp.svg"
        fig.save(str(out_file))
        # Post processing
        svg = out_file.read_text().splitlines()

    # Remove 

def _transform(self, element, transform_list):
        for t in transform_list:
            element = GroupElement([element])
            element.moveto(0, t['height'])
        return element