Problems with fold expressions in c++

I was trying to create some debug functions and ran in a problem with fold expressions.
I am new with ue4 so sorry if this question is too basic.
My function that has error:

template<typename ...Args>
FString createString(Args&&... args)
{
    std::stringstream ss;
    (ss <<... << args);
    return FString(ss.str().c_str());
}

error: error C2059: syntax error: ‘…’

This function is supposed to join values from function parameters into single string

example:

createString(123, " hello ", "world");

expected output: 123 hello world

Is there any way how to fix error or is there any neat way how to do this other way?