Return interfaces counters.

def get_interfaces_counters(self):
        """Return interfaces counters."""
        query = junos_views.junos_iface_counter_table(self.device)
        query.get()
        interface_counters = {}
        for interface, counters in query.items():
            interface_counters[interface] = {
                k: v if v is not None else -1 for k, v in counters
            }
        return interface_counters