twinx() throws error in custom theme

[besselfunct]

Hi,

I'm trying to create a custom theme that has the usual settings that I would use in OriginLab for plotting. I've made a modification to wong.jl, and saved it as my own theme:

_themes[:custom] = PlotTheme(
    palette = expand_palette(colorant"white", wong_palette; lchoices [57], cchoices = [100]),
    colorgradient = cgrad(:viridis).colors,
    legend = :false,
    grid = :false,
    twinx(),
    xmirror = :true,
)

However, when I try using Plots with this custom theme, it fails to compile throwing an error about twinx not defined

Is there another syntax for generating a "full" plot (with mirrored x and y axes with tick labels) that could be passed as an argument in a custom theme? After looking over the source code, it looks like twinx() is a function that should be callable, but is maybe getting compiled after PlotThemes.jl?