$n = 4
  matched 'fred2...' at pos 12 (gobbled '.....fred1..fred')
  matched 'fred3....' at pos 20 (gobbled '2...fred')
$n = 5
  matched 'fred1..' at pos 5 (gobbled '.....fred1')
  matched 'fred3....' at pos 20 (gobbled '..fred2...fred3')