Use LaTeX symbols (like \prime) in variables

edit

So as we know declarations such as theta=var("theta") when output as LaTeX, they're automatically converted to corresponding LaTeX symbols ($\theta$ in this case), but it makes me wonder is it possible for us to use more complicated symbols? Like thetaprime=var("\\theta\\prime") (which obviously doesn't work, I've tried), but I would like to achieve something like this, so when I call latex(eq), all thetaprime variables are converted to $\theta\prime$.