Generating Large Prime Numbers with Py Crypto

I'm trying to generate a large prime number (2048 bits) using the crypto library in python in order to implement RSA. However, I do not really understand the syntax of the getPrime() function. I currently have:

from Crypto.Util import number

n_length = 2048

primeNum = number.getPrime(n_length, randFunc)

I don't understand what the randFunc is supposed to be in the getPrime function.