Python dictionary to xml string

dict_to_xml.py

from xml.etree.ElementTree import Element, tostring

def dict_to_xml(tag: str, d: dict) -> str:
    """
    Converts a Python dictionary to an XML tree, and then returns
    it as a string.
    Works with recursively nested dictionaries!
    "tag" is the name of the top-level XML tag.
    """
    elem = Element(tag)

    def _d_to_x(elem, d):
        for key, val in d.items():
            child = Element(key)
            if isinstance(val, dict):
                elem.append(_d_to_x(Element(key), val))
            else:
                child.text = str(val)
                elem.append(child)
        return elem

    return tostring(_d_to_x(elem, d)).decode("utf-8")

Thanks for this!
A small addition, if you like. To also use pretty formatting with an indent, and handle lists.
List elements will be added with the same root name, e,g, something like

{'object': [
 {'b': 1},
 {'b': 2}
]}

will be converted to:

<root>
  <object>
    <b>1</b>
  </object>
  <object>
    <b>2</b>
  </object>
</root>

Here's the modification:

from xml.etree.ElementTree import Element, tostring
from xml.dom import minidom

def dict_to_xml(tag: str, d: dict, indent=2):
    elem = Element(tag)

    def _d_to_x(elem, d):
        for key, val in d.items():

            if not isinstance(val, list):
                child = Element(key)

            if isinstance(val, dict):
                elem.append(_d_to_x(Element(key), val))
            elif isinstance(val, list):
                for l in val:
                    elem.append(_d_to_x(Element(key), l))
            else:
                child.text = str(val)
                elem.append(child)

        return elem

    # prettify
    xml_string = tostring(_d_to_x(elem, d)).decode("utf-8")
    xml_string = minidom.parseString(xml_string)
    xml_string = xml_string.toprettyxml(indent=' ' * indent)  

    return xml_string