<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def ports_mapping(self, ports):
 """ Set the ports on this cloud. :param ports: ports info """


        if ports != self._ports_mapping:
            if len(self._nios) > 0:
                raise NodeError("Can't modify a cloud already connected.")

            port_number = 0
            for port in ports:
                port["port_number"] = port_number
                port_number += 1

            self._ports_mapping = ports