mod134.hs:6:19: error:
    Not in scope: ‘Prelude.head’
    Perhaps you meant one of these:
      ‘Prelude.read’ (imported from Prelude),
      ‘Prelude.reads’ (imported from Prelude),
      data constructor ‘Prelude.Left’ (imported from Prelude)
    Perhaps you want to remove ‘head’ from the explicit hiding list
    in the import of ‘Prelude’ (mod134.hs:4:1-28).