> block
<roxy_block> [<text>:5]
  $tag
    [line:  1] @title 'This is a title' {parsed}
    [line:  3] @param 'x,y A number' {parsed}
    [line:  4] @export '' {parsed}
    [????:???] @usage '<generated>' {parsed}
    [????:???] @.formals '<generated>' {parsed}
    [????:???] @backref '<text>' {parsed}
  $call   f <- function(x, y) x + y
  $object <function> 
    $topic f
    $alias f

