Python 3 ASCII spinner for progress feedback

spinner.py

import itertools
import sys

def spinner(granularity):
    """Wraps a function in an ASCII spinner display loop. granularity
    represents the number of times the function should be called
    before moving the spinner."""
    spinner_chars = itertools.cycle("\|/-")
    def make_spinner(f):
        calls = 0        
        def g(*args, **kwargs):
            nonlocal calls
            nonlocal granularity
            result = f(*args, **kwargs)
            if calls == 0:
                sys.stdout.write("\b" + next(spinner_chars))
                sys.stdout.flush()
            calls = (calls + 1) % granularity
            return result
        return g
    return make_spinner

# example:

# import time
# @spinner(10)
# def process_chunk():
#     time.sleep(.1)

# sys.stdout.write("running... ")
# while True:
#     process_chunk()