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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 attach_network_interface(device_index, name=None, network_interface_id=None,
                             instance_name=None, instance_id=None,
                             region=None, key=None, keyid=None, profile=None):
    '''
    Attach an Elastic Network Interface.

    .. versionadded:: 2016.3.0

    CLI Example:

    .. code-block:: bash

        salt myminion boto_ec2.attach_network_interface my_eni instance_name=salt-master device_index=0
    '''
    if not salt.utils.data.exactly_one((name, network_interface_id)):
        raise SaltInvocationError(
            "Exactly one (but not both) of 'name' or 'network_interface_id' "
            "must be provided."
        )

    if not salt.utils.data.exactly_one((instance_name, instance_id)):
        raise SaltInvocationError(
            "Exactly one (but not both) of 'instance_name' or 'instance_id' "
            "must be provided."
        )

    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)
    r = {}
    result = _get_network_interface(conn, name, network_interface_id)
    if 'error' in result:
        return result
    eni = result['result']
    try:
        info = _describe_network_interface(eni)
        network_interface_id = info['id']
    except KeyError:
        r['error'] = {'message': 'ID not found for this network interface.'}
        return r

    if instance_name:
        try:
            instance_id = get_id(name=instance_name, region=region, key=key,
                                 keyid=keyid, profile=profile)
        except boto.exception.BotoServerError as e:
            log.error(e)
            return False

    try:
        r['result'] = conn.attach_network_interface(
            network_interface_id, instance_id, device_index
        )
    except boto.exception.EC2ResponseError as e:
        r['error'] = __utils__['boto.get_error'](e)
    return r