Using setIn() to change a temp state variable

Thanks Chris. So, just to expand on this, you wrote:

The first param of setIn provides an array of keys which resolve to the point within the data structure to update.

Is it correct that:

1.) The array must always have two elements
2.) The first must be an array index
3.) The second must be an object name

What if my temp state variable is formatted differently? What if it's just an object?