human
I wrote the below code

    null = object()
    def multi_cat(*paths):
        'Attempt    to    read    the    content    of    multiple    files    which    may\n                                not    exist.    If    none    of    them    exist    return    None.\n                                '
        for path in paths:
            ret = cat(path, fallback=null)
            if (ret != null):
                return (int(ret) if ret.isdigit() else ret)
        return None
    root = os.path.join(POWER_SUPPLY_PATH, 'BAT0')
    if (not os.path.exists(root)):
        return None
    energy_now = multi_cat((root + '/energy_now'), (root + '/charge_now'))
    power_now = multi_cat((root + '/power_now'), (root + '/current_now'))
    energy_full = multi_cat((root + '/energy_full'), (root + '/charge_full'))
    if ((energy_now is None) or (power_now is None)):
        return None
    if (energy_full is not None):
        try:
            percent = ((100.0 * energy_now) / energy_full)
        except ZeroDivisionError:
            percent = 0.0
    else:
        percent = int(cat((root + '/capacity'), fallback=(-1)))
        if (percent == (-1)):
            return None
    power_plugged = None
    online = multi_cat(os.path.join(POWER_SUPPLY_PATH, 'AC0/online'), os.path.join(POWER_SUPPLY_PATH, 'AC/online'))
    if (online is not None):
        power_plugged = (online == 1)
    else:
        status = cat((root + '/status'), fallback='', binary=False).lower()
        if (status == 'discharging'):
            power_plugged = False
        elif (status in ('charging', 'full')):
            power_plugged = True
    if power_plugged:
        secsleft = _common.POWER_TIME_UNLIMITED
    else:
        try:
            secsleft = int(((energy_now / power_now) * 3600))
        except ZeroDivisionError:
            secsleft = _common.POWER_TIME_UNKNOWN
    return _common.sbattery(percent, secsleft, power_plugged)

What's a good function header?
assistant
#Here's a good function header.

def sensors_battery():