`private` is important to use in nested for loops

private-in-loops.sqf

// not using private for `_i`

_x = "";   
for [{_i = 1}, {_i <=2}, {_i = _i + 1}] do {    
    _x = _x + "o";   
   
    for [{_i = 1}, {_i <= 2}, {_i = _i + 1}] do {    
        _x = _x + "i";
    };       
};   
_x == "oii" // welp. inner loop re-used the outer variable

// do use private to prevent re-using 

_x = "";   
for [{_i = 1}, {_i <=2}, {_i = _i + 1}] do {    
    _x = _x + "o";   
   
    for [{private _i = 1}, {_i <= 2}, {_i = _i + 1}] do {    
        _x = _x + "i";
    };       
};   
_x == "oiioii"
// yay.

// HINT functions do inherit the scope from the caller. 
// a `for` loop in, say, a CBA event loop may create an _i that you inadvertently re-use.