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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 port_add(br, port, may_exist=False, internal=False):
    '''
    Creates on bridge a new port named port.

    Returns:
        True on success, else False.

    Args:
        br: A string - bridge name
        port: A string - port name
        may_exist: Bool, if False - attempting to create a port that exists returns False.
        internal: A boolean to create an internal interface if one does not exist.

    .. versionadded:: 2016.3.0

    CLI Example:
    .. code-block:: bash

        salt '*' openvswitch.port_add br0 8080
    '''
    param_may_exist = _param_may_exist(may_exist)
    cmd = 'ovs-vsctl {2}add-port {0} {1}'.format(br, port, param_may_exist)
    if internal:
        cmd += ' -- set interface {0} type=internal'.format(port)
    result = __salt__['cmd.run_all'](cmd)
    retcode = result['retcode']
    return _retcode_to_bool(retcode)