provide:
   add-two-macro
   try-expand


ast-as-array(ast) =
   let contents = ast.map with match ->
      Array? arr -> ast-as-array{arr}
      x -> #value{x}
   #data{*contents}


macro try-expand(expr) =
   try:
      let expanded-ast = @expand(@context, expr)
   catch err:
      let msg = '{err.name}: {err.message}'
      return `{false, ^=msg}`
   `{true, ^ast-as-array(expanded-ast)}`


add-two(x) = x + 1


macro{add-two} add-two-macro(#data{#value{Number? v}}) =
   let {=> add-two} = @deps
   ```
   [^add-two](^=v)
   ```