(b)every transaction (whether by way of becoming a member of, or acquiring shares in, a co-operative society, company or other association of persons or by way of any agreement or any arrangement of whatever nature whereby a person acquires any rights in or with respect to any building or part of a building (whether or not including any machinery, plant, furniture, fittings or other things therein) which has been constructed or which is to be constructed [not being a transaction by way of sale, exchange or lease of such building or part of a building which is required to be registered under the Registration Act, 1908 (16 of 1908), shall be reduced to writing in the form of a statement by each of the parties to such transaction or by any of the parties to such transaction acting on behalf of himself and on behalf of the other parties.