Answer by bdsl for How to call a PHP function within a function when the main functions is in a WordPress Plugin and uses return?

If you return a value from the myMenu function, you can assign it to a variable in the myPage function. Something like this:

function myMenu() {  return "menu";}function myPage() {  $content = myMenu();  $content .= 'abc';  $content .= 'def';  return $content;}