<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _artifact_base(self):
 """ Build the artifact basename """

        if '_artifact_base' not in self._memo:
            for artifact in self._artifacts:
                if self.re_target.search(artifact['name']) is not None:
                    artifact_base = os.path.splitext(artifact['name'])[0]
                    break
            else:
                raise FetcherException('Could not find build info in artifacts')
            self._memo['_artifact_base'] = artifact_base
        return self._memo['_artifact_base']