function with 'self' input parameter errors out with and without 'self' called

[deanhystad]

I think Yoriz's solution is good if your method uses event when an event argument is provided. I don't like so much as a way to make your function callable with zero or one arguments. I don't like the idea of twisting the function arguments to fit the vagaries of who may be calling it. If you wanted to make everyone happy you could do this:

def updateMainTasks(*_):

This allows for zero or more position arguments, all of which are unused. Such code is best avoided unless you really need it.

[Yoriz]

If you want to make everyone happy only use an event handler as an event handler with the correct parameters.
If you want the same functionality that happens in the event handler create a separate function that does what is required and call that function from the event handler function.

[deanhystad]

In my earlier example updateMainTasks(), with no arguments, is the function that does what you want done. The lambda expression creates the event handler function, with the correct arguments, that calls updateMainTasks().