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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 add_port(zone, port, permanent=True):
    '''
    Allow specific ports in a zone.

    .. versionadded:: 2015.8.0

    CLI Example:

    .. code-block:: bash

        salt '*' firewalld.add_port internal 443/tcp
    '''
    cmd = '--zone={0} --add-port={1}'.format(zone, port)

    if permanent:
        cmd += ' --permanent'

    return __firewall_cmd(cmd)