<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _relabel_to_obo(d):
 """Change the keys of ``d`` to use Obo labels. """

        return {
            owl_to_obo.get(old_k, old_k): old_v
                for old_k, old_v in six.iteritems(d)
        }