code: def serialize_value_list(self, list_elem, thelist):
          
          for value in thelist:
              value_elem = SubElement(list_elem, 'value')
              self.serialize_value(value_elem, value)
          return list_elem
docs: Serializes a list, where the values are objects of type
          str, Attrib, or PathAttrib.
  
          Example::
  
              <value>text</value>
              <value><attribute>foobar</attribute></value>
              <value><path>foobar</path></value>