If one has multiple axes, e.g. https://plot.ly/python/axes/#fixed-ratio-axes
Then how do you also add a shape, e.g. https://plot.ly/python/shapes/#vertical-and-horizontal-lines-positioned-relative-to-the-axes and specify which axes the shape should use.
Normally, when doing a plot you would do something like:
yaxis = "y2". But this does not work with shapes.