title: Loading a file using R & plumber
body: <p>I'm trying to use plumber to predict the value of a cost. For the prediction part, I saved my model in a <code>.rda</code> file. Idon't know how to load it in Plumber, Is it possible to load it just like in plane R ?
  I saw a similar <a href="https://stackoverflow.com/questions/44185675/get-file-through-api-call-r-plumber">question</a>, but I don't get how to use the functions in Jeff Allen's answer.</p>