William owns a building that is leased to Lester's machine shop. Lester request that William rewire the building for new equipment Lester plans to purchase .The wiring would cost about $4000, but would not increase the value of the building because its only use is in connection with specialized equipment. Rather than lose Laster as a lessee, William agrees to forgo one month's rent of $1000 if Lester will pay for the wiring. Because Laster does not want to move, he agrees. What amount, if any, must William include in gross income?