@classmethod
def get(cls, session, parent=None):
    """Gets all of the Clusters from the APIC.

        :returns: Instance of Cluster class.
        """
    infra_query_url = '/api/node/class/infraCont.json'
    ret = session.get(infra_query_url)
    cluster_info = ret.json()['imdata']
    infra_cluster_url = '/api/node/class/infraClusterPol.json'
    ret = session.get(infra_cluster_url)
    ret_cluster = ret.json()['imdata']
    cluster = cls('apic-cluster', parent=parent)
    cluster.config_size = ret_cluster[0]['infraClusterPol']['attributes'][
        'size']
    for apic in cluster_info:
        cluster.apics.append(apic['infraCont']['attributes']['dn'])
    cluster._populate_from_attributes(cluster_info[0]['infraCont'][
        'attributes'])
    return cluster
