public Marker pop(){
  try {
    int idx=(trail.size() - 2);
    return (idx < 0) ? backTo(0) : backTo(idx);
  }
 catch (  AMConsoleException e) {
    return null;
  }
}

public Marker pop ( ) { try { int idx = ( trail . size ( ) - 2 ) ; return ( idx < 0 ) ? backTo ( 0 ) : backTo ( idx ) ; } catch ( AMConsoleException e ) { return null ; } }
pops the last item in the list .
