norm ExpA (VarE v) = lookupSubst VarA v ExpA (VarE <$> norm VarA v)
norm ExpA (VarE v) = lookupSubst VarA v ExpA (VarE <$> norm VarA v)
norm ExpA (VarE v) = lookupSubst VarA v ExpA (VarE <$> norm VarA v)