Let’s say I have the following MWE

```
using Plots
x = y = range(0, stop=π, length=100)
z = cos.(x) .+ sin.(y')
w = cos.(x).^2 .- sin.(y').^2
contour(x,y,z, levels=1)
```

I would like the lines from the contour plot of `z`

to be coloured using the values of `w`

. Is this possible in some way?

One approach I tried is extracting the contours manually using `Contour.jl`

but I got stuck on how to extract the contour mask to apply to `w`

so I can use the `line_z`

kwarg. (see Contour.jl: extract the indices of the contour)

Thoughts? I would love to do this using `Plots.jl`

since that’s what my entire code base is based on but I am open to solutions since I have been stuck on this for a while now.