Acetylene resembles ethylene in that, although being a poor dienophile itself, it adds to...

Acetylene resembles ethylene in that, although being a poor dienophile itself, it adds to dienes when its triple bond bears electron-attracting substituents. The reaction of 1,3-butadiene with diethyl acetylenedicarboxylate gives a Diels–Alder adduct in 98% yield. What is that product?