def _embed_font_to_svg(filepath, font_files):
    """ Return the ElementTree of the SVG content in `filepath`
    with the font content embedded.
    """
    with open(filepath, 'r') as svgf:
        tree = etree.parse(svgf)

    if not font_files:
        return tree

    fontfaces = FontFaceGroup()
    for font_file in font_files:
        fontfaces.append(FontFace(font_file))

    for element in tree.iter():
        if element.tag.split("}")[1] == 'svg':
            break

    element.insert(0, fontfaces.xml_elem)

    return tree
Return the ElementTree of the SVG content in `filepath`
    with the font content embedded.