code: def parse_error(self, tup_tree):
          
  
          self.check_node(tup_tree, 'ERROR', ('CODE',), ('DESCRIPTION',),
                          ('INSTANCE',))
  
          # self.list_of_various() has the same effect as self.list_of_same()
          # when used with a single allowed child element, but is a little
          # faster.
          instance_list = self.list_of_various(tup_tree, ('INSTANCE',))
  
          return (name(tup_tree), attrs(tup_tree), instance_list)
docs: Parse the tuple for an ERROR element:
  
            ::
  
              <!ELEMENT ERROR (INSTANCE*)>
              <!ATTLIST ERROR
                  CODE CDATA #REQUIRED
                  DESCRIPTION CDATA #IMPLIED>