Merges all txt file the current folder and create a new file with all contents

mergealltxt.py

import shutil
import glob
outfilename = "all.txt"
with open(outfilename, 'wb') as outfile:
    for filename in glob.glob('*.txt'):
        if filename == outfilename:
            # don't want to copy the output into the output
            continue
        with open(filename, 'rb') as readfile:
            shutil.copyfileobj(readfile, outfile)