NameError is not defined in leetcode problem

Please bear with me, I’m still getting used to OOP in python. I’m preparing for coding interviews, and find that Leetcode problems generally have the following structure.

class Solution:
   def solutionMethod(self, input):
      ...

I want to make an object to store and update data as I proceed through my solution. I structure my code as follows:

class Solution:

   def helperMethod(self, helperInput):
      self.var1 = helperInput[0]
      self.var2 = helperInput[1]
      self.var3 = self.var1 + self.var2

   def solutionMethod(self, input):
      
      currObject = helperMethod(input)
      # do stuff with currObject
      ...

I get the nameerror: name ‘helperMethod’ is not defined.

I am thrown off because I would normally What am I doing wrong here? Do I need an init to be able to call helperMethod?

Is making a class like this generally a good idea when in the time constrained coding interview?

And is there anything I should be aware of with how leetcode (and coding interview stations) test my code? I imagine it runs as follows, is it correct?

soln = Solution()
soln.solutionMethod(input)

Answer

You need to invoke the method on the self object:

class Solution:
   def solutionMethod(self, input):
      currObject = self.helperMethod(input)