Having Returning Anonymous Function Access Global Function

I have no idea how to get an anonymous function that returns a value to source a global function? If I have a normal anonymous function, everything works fine. If the anonymous function returns, then it doesn't work? Is there any way to get this to work? Example:

/ /global function
function _myGlobalFunct(str){
return (str);
}

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the following anonymous function calls global function and it works as expected:

// working anonymous function
 (function () {
 window._myGlobalFunct("value1");
 })()

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but the following return anonymous function doesn't call my function but doesn't throw any errors? :

// Not Working Properly but doesn't throw any errors?
return (function() { 
  var rvalue = document.title || "No Title";
 window._myGlobalFunct(rvalue);
return rvalue;
})();

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