def METHOD_NAME(self):
	bld = self.generator.bld
	sig = self.signature()
	for node in self.outputs:
		if not node.exists():
			self.hasrun = MISSING
			self.err_msg = '-> missing file: %r' % node.abspath()
			raise Errors.WafError(self.err_msg)
		os.setxattr(node.abspath(), 'user.waf.sig', sig)
	if not self.outputs:
		# only for task with no outputs
		bld.task_sigs[self.uid()] = sig
	if not self.keep_last_cmd:
		try:
			del self.last_cmd
		except AttributeError:
			pass