'Takes a list of hosts. Add the hosts to the model without going
over the maximun size of the model. Return None.'

def add_relevant_hosts_to_model(self, hosts):

    space_left_in_sidebar = (20 - self.host_amount_in_model)
    relevant_hosts = hosts[0:space_left_in_sidebar]
    map(self._add_single_host_to_model, relevant_hosts)
