From the March-April 2019 issue of Acoustic Guitar | BY ADAM PERLMUTTER (Video by Al Petteway) Not long ago, the editors of this magazine decided it was high time to run an arrangement of a Celtic tune, so I emailed the diverse fingerstyle master Al Petteway for suggestions. Sure enough, Petteway replied in moments with a great idea: “O’Farrell’s Farewell…