#!/usr/bin/python -uimport libxml2import sys ARG = 'test string' class ErrorHandler:     def __init__(self):        self.errors = []     def handler(self, msg, data):        if data != ARG:            raise Exception, "Error handler did not receive correct argument"        self.errors.append(msg)  # Memory debug specificlibxml2.debugMemory(1) dtd="""<!ELEMENT foo EMPTY>"""valid="""<?xml version="1.0"?><foo></foo>""" invalid="""<?xml version="1.0"?><foo><bar/></foo>""" dtd = libxml2.parseDTD(None, 'test.dtd')ctxt = libxml2.newValidCtxt()e = ErrorHandler()ctxt.setValidityErrorHandler(e.handler, e.handler, ARG) # Test valid documentdoc = libxml2.parseDoc(valid)ret = doc.validateDtd(ctxt, dtd)if ret != 1 or e.errors:    print "error doing DTD validation"    sys.exit(1)doc.freeDoc() # Test invalid documentdoc = libxml2.parseDoc(invalid)ret = doc.validateDtd(ctxt, dtd)if ret != 0 or not e.errors:    print "Error: document supposed to be invalid"doc.freeDoc() dtd.freeDtd()del dtddel ctxt # Memory debug specificlibxml2.cleanupParser()if libxml2.debugMemory(1) == 0:    print "OK"else:    print "Memory leak %d bytes" % (libxml2.debugMemory(1))    libxml2.dumpMemory()