MathJax Macros with arguments

[haakon-e]

I'm trying to follow the docs to create my own macros, but am struggling with certain ones. For example, how would I create either of these macros in a way that works?

mathengine = Documenter.MathJax3(Dict(:TeX => Dict(
    :equationNumbers => Dict(:autoNumber => "AMS"),
    :Macros => Dict(
        :t => ["\\text#1", 1],
        :dx => ["\\frac{d#2}{d#1}", 2, "x"],
    ),
)))

(the latter is from mathjax docs).