I'm trying to pass a function as a parameter but it throws 'Unit cannot be invoked as function. Thanks in advance. 

```
uploadImageToParse(imageFile, saveCall1())
uploadImageToParse(imageFile, saveCall2())
uploadImageToParse(imageFile, saveCall3())

private fun uploadImageToParse(file: ParseFile?, saveCall: Unit) {
        saveCall()//Throws an error saying 'Unit cannot be invoked as function'
} 

```