Python: Generate svg file from custom config

[openHacking]

from lxml import etree
# reference: https://shayallenhill.com/svg-with-css-in-python/

def new_svg():
    my_root_element = etree.Element(
        "svg", width='640', height='480', xmlns="http://www.w3.org/2000/svg"
    )

    # let's draw a rectangle
    my_rectangle = etree.Element(
        # the svg element type
        "rect",
        # any svg parameters that happen to be valid
        # Python attribute names
        x="13",
        y="14",
        width="500",
        height="200",
        rx="50",
        ry="100",
        stroke="blue",
    )

    my_root_element.append(my_rectangle)

    # another rectangle
    my_rectangle_string = etree.fromstring(
        f'<rect class="some-css-class" x="13" y="214" width="500" height="200" stroke="red" />'
    )

    my_root_element.append(my_rectangle_string)

    # we must add style
    style = etree.Element("style", type="text/css")
    style.text = etree.CDATA("/** some CSS **/")
    my_root_element.insert(0, style)

    # generate svg content string
    return etree.tostring(
            etree.ElementTree(my_root_element),
            xml_declaration=True,
            doctype=(
                '<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" '
                '"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">'
            ),
        )


# Writing a file
f = open('file.svg', 'wb+')
f.write(new_svg())

f.close()