$(document).ready(function(){
  $('.switcher').each(function() {
    var sid = $(this).attr('id'); // sid = switch_to_N_L
    var number = sid.substring(10, 11);
    var letter = sid.substring(12, 13);
    var my_letter = (letter == 'a' ? 'b' : 'a');
    $(this).click(function() {
      $('#switch_' + number + '_' + my_letter).hide();
      $('#switch_' + number + '_' + letter).show();
    });
  });
});