means any person who carries on any trade, business, industry or undertaking in which property is sold, or is bought, exchanged or manufactured for purpose of sale or exchange, or in which building operations of whatever nature are performed, or an object whereof is public entertainment, or who carries on the business of an hotel keeper or boarding-house keeper, or who acts as a broker or agent of any person in the sale or purchase of any property or in the letting or hiring of immovable property; and any person shall be deemed to be a trader for the purpose of this Act (except for the purposes of subsection (10) of section twenty-one) unless it is proved that he is not a trader as hereinbefore defined: Provided that if any person carries on the trade, business, industry or undertaking of selling property which he produced (either personally or through any servant) by means of farming operations, the provisions of this Act relating to traders only shall not apply to him in connection with his said trade, business, industry or undertaking;