Python Classes ( AttributeError: '' object has no attribute '')

Question

Having trouble understanding the problem in my code, new to classes (generally python too, so sorry if I name things wrong). I receive this error:

I think my code is too long winded to include in here, so I made a simplified version to test the concept below.

The question is, how can I create a new self object "self4"? Which would then be available to other functions within the class. Currently I get this error.

AttributeError: 'className' object has no attribute 'self4'

class className(object):

   def __init__(self, self1=1,self2=2,self3=3):
        self.self1=self1
        self.self2=self2
        self.self3=self3

   def evaluate(self, self5):
        print className.func1(self) + className.func2(self)
        self.self5=self5
        print className.func1(self)

   def func1(self):
       return self.self1 + self.self5

   def func2(self):
       self.self4 = self.self1+self.self2+self.self3
       return self.self4

filename tester.py

import tester.py

mst=tester.className()

mst.evaluate()

Answer 1

Edit:
Your code works fine!
What is the Problem?

I still think it is better to move self4 into the init!

Original
I think the most logical thing would be to define self4 on init:

class className(object):
    def __init__(self, self1=1, self2=2, self3=3):
        self.self1 = self1
        self.self2 = self2
        self.self3 = self3
        self.self4 = None

   #rest of class