mod73.hs:3:7: error:
    Not in scope: ‘Prelude.g’
    Perhaps you meant one of these:
      data constructor ‘Prelude.GT’ (imported from Prelude),
      data constructor ‘Prelude.EQ’ (imported from Prelude),
      data constructor ‘Prelude.LT’ (imported from Prelude)
    Module ‘Prelude’ does not export ‘g’.