Is it correct to state that $u$ is a universal function if and only if

begin{align}

forall f : mathrm{RE} quad

exists g : mathrm{R} quad

exists h : mathrm{R} quad

f = h circ u circ g

end{align}

where RE is the set of recursively enumerable functions and R is the set of recursive functions? (Should R be replaced with something like PR?) If so, does anyone know of a reference that states universality in this generic form?