 Definition 2.1:   Suppose that \(f:\mathbb{N}^j \rightarrow \mathbb{N}\) and \(g_0, \ldots, g_{j-1} : \mathbb{N}^k \rightarrow \mathbb{N}\). Then the term \(\mathcal{Comp}^j_k[f,g_0,\ldots,g_{j-1}]\) denotes the function