Section 20. If at the examination of the debtor it appears that after service of supplementary process, the debtor has made a payment of money or a conveyance, assignment or transfer of property which is not exempt from being taken on execution, with intent to prevent it from being transferred or paid to the creditor or applied to the satisfaction of the judgment, and the court so certifies, the debtor or, in the case of a corporation or trust with transferable shares, its officer, trustee or agent as provided in section sixteen, may in the discretion of the court be committed as for a contempt. The payment by the debtor of a debt for necessaries, or a debt due on any judgment on which he or it has previously been summoned to appear in supplementary proceedings, or a reasonable fee for counsel relative to the proceedings, shall not render him or it liable for contempt.