  We consider a non-static evolving version of the regular
"black-bounce"/traversable wormhole geometry recently introduced in
JCAP02(2019)042 [arXiv:1812.07114 [gr-qc]]. We first re-write the static metric
using Eddington-Finkelstein coordinates, and then allow the mass parameter $m$
to depend on the null time coordinate (a la Vaidya). The spacetime metric is \[
ds^{2}=-\left(1-\frac{2m(w)}{\sqrt{r^{2}+a^{2}}}\right)dw^{2}-(\pm 2 \,dw \,dr)
+\left(r^{2}+a^{2}\right)\left(d\theta^{2}+\sin^{2}\theta \;d\phi^{2}\right).
\] Here $w=\{u,v\}$ denotes the $\{outgoing,ingoing\}$ null time coordinate;
representing $\{retarded,advanced\}$ time. This spacetime is still simple
enough to be tractable, and neatly interpolates between Vaidya spacetime, a
black-bounce, and a traversable wormhole. We show how this metric can be used
to describe several physical situations of particular interest, including a
growing black-bounce, a wormhole to black-bounce transition, and the opposite
black-bounce to wormhole transition.
