<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def process_exists(pid=None):
 """ Evaluates a Pid Value defaults to the currently foucsed window against the current open programs, if there is a match returns the process name and pid otherwise returns None, None """

    if not pid:
        pid = current_pid()
    elif callable(pid):
        pid = pid()

    if pid and psutil.pid_exists(pid):
        pname = psutil.Process(pid).name()
        if os.name == 'nt':
            return os.path.splitext(pname)[0], pid
        return pname, pid
    return None, None