-- Test script for some command API details. local utils = require("mp.utils") function join(sep, arr, count)    local r = ""    if count == nil then        count = #arr    end    for i = 1, count do        if i > 1 then            r = r .. sep        end        r = r .. utils.to_string(arr[i])    end    return rend mp.observe_property("vo-configured", "bool", function(_, v)    if v ~= true then        return    end     print("async expand-text")    mp.command_native_async({"expand-text", "hello ${path}!"},        function(res, val, err)            print("done async expand-text: " .. join(" ", {res, val, err}))        end)     -- make screenshot writing very slow    mp.set_property("screenshot-format", "png")    mp.set_property("screenshot-png-compression", "9")     timer = mp.add_periodic_timer(0.1, function() print("I'm alive") end)    timer:resume()     print("Slow screenshot command...")    res, err = mp.command_native({"screenshot"})    print("done, res: " .. utils.to_string(res))     print("Slow screenshot async command...")    res, err = mp.command_native_async({"screenshot"}, function(res)        print("done (async), res: " .. utils.to_string(res))        timer:kill()    end)    print("done (sending), res: " .. utils.to_string(res))     print("Broken screenshot async command...")    mp.command_native_async({"screenshot-to-file", "/nonexistent/bogus.png"},        function(res, val, err)            print("done err scr.: " .. join(" ", {res, val, err}))        end)     mp.command_native_async({name = "subprocess", args = {"sh", "-c", "echo hi && sleep 10s"}, capture_stdout = true},        function(res, val, err)            print("done subprocess: " .. join(" ", {res, val, err}))        end)     local x = mp.command_native_async({name = "subprocess", args = {"sleep", "inf"}},        function(res, val, err)            print("done sleep inf subprocess: " .. join(" ", {res, val, err}))        end)    mp.add_timeout(15, function()        print("aborting sleep inf subprocess after timeout")        mp.abort_async_command(x)    end)end)