'Fetches as a list of load balancers
:return:    ``list`` of class ``ProfitBricksLoadBalancer``
:rtype:     `list`'

def ex_list_load_balancers(self):

    datacenters = self.ex_list_datacenters()
    load_balancers = list()
    for datacenter in datacenters:
        extra = datacenter.extra
        load_balancers_href = extra['entities']['loadbalancers']['href']
        response = self.connection.request(action=load_balancers_href, params={'depth': 3}, method='GET', with_full_url=True)
        mapped_load_balancers = self._to_load_balancers(response.object)
        load_balancers += mapped_load_balancers
    return load_balancers
