Assertion fail when returning an anonymous function.

In the following code example, an anonymous function is returned, acting like a closure. However, the Printer class expects a function name.

function generateComparisonFunctionForKey($key) {
        return function ($left, $right) use ($key) {
            if ($left[$key] == $right[$key])
                return 0;
            else
                return ($left[$key] < $right[$key]) ? -1 : 1;
        };
    }

Error:

Warning: assert(): Assertion failed in /Users/<redacted>/php-cfg/lib/PHPCfg/Printer.php on line 46

Start with Printer.php at line 46 and reproduce the assertion using the anonymous closure shown in the issue. Trace how Printer handles function names versus returned closures; the issue is complete when the closure case no longer triggers the assertion and its intended handling is clear.