How to organise helping functions in my code

Question

So the class I've created looks like this:

class DataProcessor(object):

    data1
    data2
    data3

    def process_data(self):
        self.process_data1_inOneWay()
        self.process_data2_inAnotherWay()
        self.process_data3_inADifferentWay()

The processing task consists of parts and my question is: what is the proper place to define those helping functions. I don't feel like they should be part of the DataProcessor class, because process_data is the only method that uses them. I considered defining an inner class, but I read that their usage isn't really encouraged. I also considered lambdas, but rejected this idea due to their limited functionality. Or maybe I should put all the code inside process_data method and don't split it into smaller parts.

Answer 1

I'd just put them into the class and give them a weak 'internal use' indicator.

According to PEP8 those method's names should have a leading underscore: _process_data1_someway().

As long as it is easily obvious what their role/intended visibility is just from reading the class definition, I would not worry too much about that.