OpenMC/openmc/clean_xml.py

def clean_xml_indentation(element, level=0, spaces_per_level=2):
    """
    copy and paste from http://effbot.org/zone/elementent-lib.htm#prettyprint
    it basically walks your tree and adds spaces and newlines so the tree is
    printed in a nice way
    """

    i = "\n" + level*spaces_per_level*" "

    if len(element):

        if not element.text or not element.text.strip():
            element.text = i + spaces_per_level*" "

        if not element.tail or not element.tail.strip():
            element.tail = i

        for sub_element in element:
            clean_xml_indentation(sub_element, level+1, spaces_per_level)

        if not sub_element.tail or not sub_element.tail.strip():
            sub_element.tail = i

    else:
        if level and (not element.tail or not element.tail.strip()):
            element.tail = i