readframes return 2 byte in python

When readframes() is used in python, the online documention says sampling frequency is returned it looks it returns 2 bytes. I think there are 4 byte on each frame:

left = 2 bytes
right = 2 bytes

Do I have to check if it is mono or stereo and if it is stereo, read 2 frames at a time and if it is mono, read 1 frame at a time?