UFile (package = )
    UClass (name = AssertionKt)
        UMethod (name = foo)
            UBlockExpression
                UDeclarationsExpression
                    ULocalVariable (name = s)
                        ULiteralExpression (value = "Not Null")
                UReturnExpression
                    UPostfixExpression (operator = !!)
                        USimpleNameReferenceExpression (identifier = s)
