How to extract the body of a function?

New to Julia
3

It’s nice to get something like

(:function, (:call, :fun, (:(::), :n, :Int)), 
(:block,
    (:line, 2, :none),
    (:(=), :s, (:call, :*, 2, :n)),
    (:line, 3, :none),
    (:call, :println, :s)
  ))

but how can I proceed from this back to the required form

["s = 2 * n", "println(s)"]