Callables vs functions

["Thiago L." <fakedme@...>]

<SoniEx2> %5.3 t=setmetatable({")", "'test'", "print("},{__call = function(t,...) return table.remove(t) end}) load(t)()
<yalb> SoniEx2: sandbox:1: bad argument #1 to 'load' (function expected, got table); stack traceback:; [C]: in function 'load'; sandbox:1: in main chunk

Can we please get a callable API? (for example, iscallable(obj), or in C, lua_iscallable(whatever))