law: 173. Mutual credit and set-off.-
  (1) Where before the bankruptcy commencement date, there have been mutual dealings between the bankrupt and any creditor, the bankruptcy trustee shall-
  (a) take an account of what is due from each party to the other in respect of the mutual dealings and the sums due from one party shall be set-off against the sums due from the other; and
  (b) only the balance shall be provable as a bankruptcy debt or as the amount payable to the bankruptcy trustee as part of the estate of the bankrupt.
  (2) Sums due from the bankrupt to another party shall not be included in the account taken by the bankruptcy trustee under sub-section (1), if that other party had notice at the time they became due that an application for bankruptcy relating to the bankrupt was pending.