code: def distance_to_current_waypoint():
      
      nextwaypoint = vehicle.commands.next
      if nextwaypoint==0:
          return None
      missionitem=vehicle.commands[nextwaypoint-1] #commands are zero indexed
      lat = missionitem.x
      lon = missionitem.y
      alt = missionitem.z
      targetWaypointLocation = LocationGlobalRelative(lat,lon,alt)
      distancetopoint = get_distance_metres(vehicle.location.global_frame, targetWaypointLocation)
      return distancetopoint
docs: Gets distance in metres to the current waypoint. 
      It returns None for the first waypoint (Home location).