code: def _find_element_text(element, match, default=None):
      
      child = element.find(match)
      try:
          return child.text
      except AttributeError:
          if default is not None:
              return default
          else:
              raise MissingElementError(element, match)
docs: Find a matching subelement and return its text.
  
      If default is given, return it if a matching subelement is not
      found.  Otherwise, ValueError is raised.