<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def tracker_class(clsname):
 """Get class instance details."""

    stats = server.stats
    if not stats:
        bottle.redirect('/tracker')
    stats.annotate()
    return dict(stats=stats, clsname=clsname)