In any claim, action, or proceeding brought under this article, the signature of an attorney or party constitutes a certificate by him or her that he or she has read the pleading, motion, or other paper; that to the best of his or her knowledge, information, and belief formed after reasonable inquiry it is well grounded in fact and is warranted by existing law or a good faith argument for the extension, modification, or reversal of existing law; and that it is not interposed for any improper purpose, such as to harass or to cause unnecessary delay or needless increase in the cost of litigation. If a pleading, motion, or other paper is not signed, it shall be stricken unless it is signed promptly after the omission is called to the attention of the pleader or movant. If a pleading, motion, or other paper is signed in violation of this Code section, the court, upon motion or upon its own initiative, shall impose upon the person who signed it, a represented party, or both an appropriate sanction, which may include an order to pay to the other party or parties the amount of the reasonable expenses incurred because of the filing of the pleading, motion, or other paper, including reasonable attorneys' fees.