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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 list_port_fwd(zone, permanent=True):
    '''
    List port forwarding

    .. versionadded:: 2015.8.0

    CLI Example:

    .. code-block:: bash

        salt '*' firewalld.list_port_fwd public
    '''
    ret = []

    cmd = '--zone={0} --list-forward-ports'.format(zone)

    if permanent:
        cmd += ' --permanent'

    for i in __firewall_cmd(cmd).splitlines():
        (src, proto, dest, addr) = i.split(':')

        ret.append(
            {'Source port': src.split('=')[1],
             'Protocol': proto.split('=')[1],
             'Destination port': dest.split('=')[1],
             'Destination address': addr.split('=')[1]}
        )

    return ret