docs: def pretty_xml(string_input, add_ns=False):
      """ pretty indent string_input """
      if add_ns:
          elem = "<foo "
          for key, value in DOC_CONTENT_ATTRIB.items():
              elem += ' %s="%s"' % (key, value)
          string_input = elem + ">" + string_input + "</foo>"
      doc = minidom.parseString(string_input)
      if add_ns:
          s1 = doc.childNodes[0].childNodes[0].toprettyxml("  ")
      else:
          s1 = doc.toprettyxml("  ")
      return s1