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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def chrootedSystemCall(chrootDir, cmd, sh=True, mountPseudoFs=True, log=None):
    '''Chrooted version of systemCall. Manages necessary pseudo filesystems.'''
    if log is None:
        log = conduct.app.log

    # determine mount points for pseudo fs
    proc = path.join(chrootDir, 'proc')
    sys = path.join(chrootDir, 'sys')
    dev = path.join(chrootDir, 'dev')
    devpts = path.join(chrootDir, 'dev', 'pts')

    # mount pseudo fs
    if mountPseudoFs:
        mount('proc', proc, '-t proc')
        mount('/sys', sys, '--rbind')
        mount('/dev', dev, '--rbind')

    try:
        # exec chrooted cmd
        log.debug('Execute chrooted command ...')
        cmd = 'chroot %s %s' % (chrootDir, cmd)
        return systemCall(cmd, sh, log)
    finally:
        # umount if pseudo fs was mounted
        if mountPseudoFs:
            # handle devpts
            if path.exists(devpts):
                umount(devpts, '-lf')
            # lazy is ok for pseudo fs
            umount(dev, '-lf')
            umount(sys, '-lf')
            umount(proc, '-lf')