How do I read/write small sections of an audio file with pysoundfile?

So I'm making a program that corrects stereo in-balance for an audio file. I'm using pysoundfile to read/write the files. Code looks something like this.

import soundfile as sf

data, rate = sf.read("Input.wav")

for d in data:
    # processes audio

sf.write("Output.wav", data, rate, 'PCM_24')

The issue is that I'm working with DJ mixes that can be a couple hours long. So loading the entire mix into ram is causing the program to be killed.

My question is how do I read/write the file in smaller sections vs loading the entire thing?