For the purpose of this article:
(a) "Contractor" includes persons who furnish work, or both materials and work, in the fulfillment of a contract for the construction, alteration, repair, decoration or improvement of a new or existing building or structure, or any part thereof, or for the alteration, improvement or development of real property. Those taxpayers classified with Section 787.03(d) and taxed according to Section 787.02(d) shall be included in this article.