not sure, don't know how to get python to write a 0 without a null terminator or EOL or anything like that yet. docs.python.org FTW.
import os
# open a file for writing f = os.open('/tmp/foobar', os.O_WRONLY)
# create a string with a single NULL byte s = '\0'
# write the string f.write(s)
# close the file f.close()