pprImm (ImmConstantDiff a b) = pprImm a <> char '-'
                            <> lparen <> pprImm b <> rparen
pprImm (ImmConstantDiff a b) = pprImm a <> char '-'
                            <> lparen <> pprImm b <> rparen
pprImm (ImmConstantDiff a b) = pprImm a <> char '-'
                            <> lparen <> pprImm b <> rparen