This function finds the distance between two points. '''Parameters:''' * 1: double x1 - x coordinate of first point. * 2: double y1 - y coordinate of first point. * 3: double z1 - z coordinate of first point. * 4: double x2 - x coordinate of second point. * 5: double y2 - y coordinate of second point. * 6: double z2 - z coordinate of second point. '''Responds:''' * ''X'' where X is the distance between the two points '''Reports:''' * ''done'' when the task completes. '''Example:''' * User sends: "fd 512 0 0 0 3 4 12" * Director replies: "rs fd 512 13.000001" * Director replies: "cp fd 512 done"