 Part iv of  Proposition 3.2  also provides a convenient uniform notation for computably enumerable sets—i.e., if \(A = \textrm{dom}(\phi_e)\) we denote \(A\) by \(W_e = \{n : \phi_e(n) \darrow\}\). The sequence \(W_0,W_1, W_2, \ldots\) thus provides a uniform enumeration of c.e. sets relative to our prior enumeration of unary partial computable functions. This notation also aids the formulation of the following: