I have this really simple function, which tries to lookup a value in the local storage:
function get_sectoken() {
    var sectoken;
    chrome.storage.local.get(null, function(obj) {
        if (obj.sectoken_val) {
            sectoken = obj.sectoken_val;
            console.log("Security token: " + sectoken);
        } else {
            console.log("Security token not found!");
        }
    });
    return sectoken;
}
If I try to assign it to a variable, I can see that console.log() has fired up:
st = get_sectoken();
Security token: UoMjWVeEeEqxeCKpRYaMmxIGAFyofEpC
But if I check what has been assigned to this variable, I see it's undefined:
st
undefined
What am I doing wrong?
