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

def nvme_nqn():
    '''
    Return NVMe NQN
    '''
    grains = {}
    grains['nvme_nqn'] = False
    if salt.utils.platform.is_linux():
        grains['nvme_nqn'] = _linux_nqn()
    return grains