You could write a create_or_get
method, that creates the path for you if one doesn't already exist. Something like:
def create_or_get(tree, nodes):
for node in nodes:
if not tree.hasElement(node):
tree.appendChild(tree.createElement(node))
tree = tree.getElement(node)
return tree
create_or_get(doc, ["Global", "Config", "Hey"]).text = "lorem ipsum dolor sit amet"