threading question

[Charles G Waldman]

When I run the trivial example attached below, which simply
starts a daemon thread that does nothing, and then type "ps",
I see *three* python processes.  I can understand two, but
why three?

Platform is Linux 2.2.10 with the most recent glibc (2.1.1),
if that matters.

Thanks in advance for any pointers.  Or, since this is Python,
better make that "references".

from threading import *        
import time

class Test:

    def __init__(self):
        self.test = Thread(group=None,
                               target=self.thread_fn,
                               name="thread1",
                               )
        self.test.setDaemon(1)
        self.test.start()

    def thread_fn(self):
        while 1:
            time.sleep(1)


if __name__ == "__main__":

    x = Test()
    while 1:
        time.sleep(1)