collections_example.py

from collections import Counter
import glob

# get list of filenames matching a pattern using glob
filenames = glob.glob("path/to/many/files/*.txt")

# create empty counter object
counts = Counter()

# loop over files, create a counter for each, and merge into counts
for file in filenames:
    with open(file) as f:
        counts += Counter(f.read().split())

# prints the 10 most common items in the Counter
# omit argument to print all items in descending order of frequency
print(counts.most_common(10))