// Flier$Ego.java [static]
public class Flier$Ego 
{
  // upstream interface. Must implement here.
  public void Fly(Flier host, int x, int y, int altitude) {
    resetMetersFlown();
    host.Takeoff();
    for (int a=0; a < altitude; a++) host.Ascend();
    while( !host.ThereYet(x, y) ) host.FlapTowards(x, y);
    for(int a = altitude; a > 0; a--) host.Descend();
    host.Land();
  }
  // private functions. Must implement here.
  private void resetMetersFlown() { meters_flown = 0; }
  // attributes (specific to the role)
  private float meters_flown;
  // constructor (optional)
  Flier$Ego( ) { 
    resetMetersFlown(); 
  }
}