In any criminal trial or proceeding where evidence of flight of a defendant is relied upon as tending to show guilt, the court shall instruct the jury substantially as follows:

The flight of a person immediately after the commission of a crime, or after he is accused of a crime that has been committed, is not sufficient in itself to establish his guilt, but is a fact which, if proved, the jury may consider in deciding his guilt or innocence. The weight to which such circumstance is entitled is a matter for the jury to determine.

No further instruction on the subject of flight need be given.