def preview(request, fec_id):
    candidates = Candidate.objects.filter(cand_id=fec_id).order_by('-cycle')
    try:
        candidate = candidates[0]
    except IndexError:
        raise Http404
    return render_to_response('reconciliation/fec_preview.html', 
       {
       'candidate':candidate,
       'candidates':candidates,
       'preview_height':PREVIEW_HEIGHT - 30,
       'preview_width':20 - PREVIEW_WIDTH
       })
dataset/ETHPy150Open sunlightlabs/read_FEC/fecreader/reconciliation/views.py/preview/swapped operands of `-`