def write_pid_file(fn):
if not fn:<EOL><INDENT>return None<EOL><DEDENT>if fn == '<STR_LIT>' or fn == "<STR_LIT>":<EOL><INDENT>return None<EOL><DEDENT>f = open(fn, "<STR_LIT:w>")<EOL>f.write("<STR_LIT>" % (os.getpid()))<EOL>f.close()<EOL>
Create a file with our PID.