<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def fetchref(self, ref):
 """Fetch a particular git ref."""

        log.debug('[%s] Fetching ref: %s', self.name, ref)
        fetch_info = self.repo.remotes.origin.fetch(ref).pop()
        return fetch_info.ref