code: def validateDocument(self, ctxt):
          
          if ctxt is None: ctxt__o = None
          else: ctxt__o = ctxt._o
          ret = libxml2mod.xmlValidateDocument(ctxt__o, self._o)
          return ret
docs: Try to validate the document instance  basically it does
            the all the checks described by the XML Rec i.e. validates
            the internal and external subset (if present) and validate
             the document tree.