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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 additions_mount():
    '''
    Mount VirtualBox Guest Additions CD to the temp directory.

    To connect VirtualBox Guest Additions via VirtualBox graphical interface
    press 'Host+D' ('Host' is usually 'Right Ctrl').

    CLI Example:

    .. code-block:: bash

        salt '*' vbox_guest.additions_mount

    :return: True or OSError exception
    '''
    mount_point = tempfile.mkdtemp()
    ret = __salt__['mount.mount'](mount_point, '/dev/cdrom')
    if ret is True:
        return mount_point
    else:
        raise OSError(ret)