### Conditional Plot, plot f(x+iy) if g(x+iy) satisfies some kind of condition

Let's say I have two functions f(zeta) and g(zeta), and I'd like to have 3D-plot and Contour Plot of f(zeta) if g(zeta) in a certain range.

I have defined f(zeta) and g(zeta), and then I tried this command, but Sage said the syntax is not valid.

```
B=implicit_plot(lambda x,y : float(f(x+y*I)),if 1<g(x+y*I)<3,(-5,5),(-5,5)))
```

I am pretty new with Sage math, so please bear with me if the question is too trivial....