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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 _linux_wwns():
    '''
    Return Fibre Channel port WWNs from a Linux host.
    '''
    ret = []
    for fc_file in glob.glob('/sys/class/fc_host/*/port_name'):
        with salt.utils.files.fopen(fc_file, 'r') as _wwn:
            content = _wwn.read()
            for line in content.splitlines():
                ret.append(line.rstrip()[2:])
    return ret