ppr_co p (TcSymCo co)         = pprPrefixApp p (ptext (sLit "Sym")) [pprParendTcCo co]
ppr_co p (TcSymCo co)         = pprPrefixApp p (ptext (sLit "Sym")) [pprParendTcCo co]
ppr_co p (TcSymCo co)         = pprPrefixApp p (ptext (sLit "Sym")) [pprParendTcCo co]