docs: def update(self, **kwargs):
          u"""Updating or creation of new simple nodes.
  
          Each dict key is used as a tagname and value as text.
          """
          for key, value in kwargs.items():
              helper = helpers.CAST_DICT.get(type(value), str)
              tag = self._get_aliases().get(key, key)
  
              elements = list(self._xml.iterchildren(tag=tag))
              if elements:
                  for element in elements:
                      element.text = helper(value)
              else:
                  element = etree.Element(key)
                  element.text = helper(value)
                  self._xml.append(element)
                  self._aliases = None