  In this paper we prove a formula for fusion coefficients of affine Kac-Moody
algebras first conjectured by Walton [Wal2], and rediscovered in [Fe]. It is a
reformulation of the Frenkel-Zhu affine fusion rule theorem [FZ], written so
that it can be seen as a beautiful generalization of the classical
Parasarathy-Ranga Rao-Varadarajan tensor product theorem [PRV].
