docs: def resolve_sid(sid):
      """Get the PID to which the ``sid`` currently maps.
  
      Preconditions:
      - ``sid`` is verified to exist. E.g., with d1_gmn.app.views.asserts.is_sid().
  
      """
      return d1_gmn.app.models.Chain.objects.get(sid__did=sid).head_pid.did