docs: def findElementsWithId(node, elems=None):
      """
      Returns all elements with id attributes
      """
      if elems is None:
          elems = {}
      id = node.getAttribute('id')
      if id != '':
          elems[id] = node
      if node.hasChildNodes():
          for child in node.childNodes:
              # from http://www.w3.org/TR/DOM-Level-2-Core/idl-definitions.html
              # we are only really interested in nodes of type Element (1)
              if child.nodeType == Node.ELEMENT_NODE:
                  findElementsWithId(child, elems)
      return elems