002 string ownership

// Test: String ownership transitions and append
~import std/string
~import std/io

~std/string:from-page(text: "hello")
| ok s |> std/string:take(s)
    | instance owned |> std/string:append(s: owned, text: " world")
        | ok |> std/string:read(s: owned)
            | slice text |> std/io:print.ln("{{ text:s }}") |> std/string:free(s: owned)
        | err _ |> std/string:free(s: owned)
| err _ |> _