question: return the track speed concode_field_sep double heading concode_elem_sep double alt concode_elem_sep double lon concode_elem_sep double time concode_elem_sep double lat concode_elem_sep double speed concode_field_sep Point4D asPoint4D concode_elem_sep double getLongitude concode_elem_sep double getAltitude concode_elem_sep double getTime concode_elem_sep double getLatitude concode_elem_sep double getHeading
target: double function ( ) { return speed ; }