<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def init(image, root=None):
    '''
    Mount the named image via qemu-nbd and return the mounted roots

    CLI Example:

    .. code-block:: bash

        salt '*' qemu_nbd.init /srv/image.qcow2
    '''
    nbd = connect(image)
    if not nbd:
        return ''
    return mount(nbd, root)