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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 get_network_mappings(network_id, network_2_id=None, **kwargs):
 """ Get all the mappings of network resource attributes, NOT ALL THE MAPPINGS WITHIN A NETWORK. For that, ``use get_mappings_in_network``. If another network is specified, only return the mappings between the two networks. """

    qry = db.DBSession.query(ResourceAttrMap).filter(
        or_(
            and_(
                ResourceAttrMap.resource_attr_id_a == ResourceAttr.id,
                ResourceAttr.network_id == network_id),
            and_(
                ResourceAttrMap.resource_attr_id_b == ResourceAttr.id,
                ResourceAttr.network_id == network_id)))

    if network_2_id is not None:
        aliased_ra = aliased(ResourceAttr, name="ra2")
        qry = qry.filter(or_(
            and_(
                ResourceAttrMap.resource_attr_id_a == aliased_ra.id,
                aliased_ra.network_id == network_2_id),
            and_(
                ResourceAttrMap.resource_attr_id_b == aliased_ra.id,
                aliased_ra.network_id == network_2_id)))

    return qry.all()