get centos uptime of a server in datetime format python

1def get_uptime(session=None):
2    """
3    Get the uptime of system in secs
4
5    :param session: VM session or remote session object, None for host
6
7    :return: uptime of system in float, None on error
8    """
9    cmd = "cat /proc/uptime"
10    if session:
11        uptime = session.cmd_output(cmd)
12    else:
13        try:
14            uptime = process.run(cmd, shell=True).stdout_text
15        except process.CmdError:
16            return None
17    return float(uptime.split()[0])