prettyPreAcc pp alvl wrap (Stencil sten bndy acc)
  = wrap 
  $ prettyArrOp "stencil" [parens (prettyPreFun pp alvl sten),
                           prettyBoundary acc bndy,
                           pp alvl parens acc]
prettyPreAcc pp alvl wrap (Stencil sten bndy acc)
  = wrap 
  $ prettyArrOp "stencil" [parens (prettyPreFun pp alvl sten),
                           prettyBoundary acc bndy,
                           pp alvl parens acc]
prettyPreAcc pp alvl wrap (Stencil sten bndy acc)
  = wrap 
  $ prettyArrOp "stencil" [parens (prettyPreFun pp alvl sten),
                           prettyBoundary acc bndy,
                           pp alvl parens acc]