<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _parse_subnet(self, subnet_dict):
 """Return the subnet, start, end, gateway of a subnet. """

        if not subnet_dict:
            return
        alloc_pool = subnet_dict.get('allocation_pools')
        cidr = subnet_dict.get('cidr')
        subnet = cidr.split('/')[0]
        start = alloc_pool[0].get('start')
        end = alloc_pool[0].get('end')
        gateway = subnet_dict.get('gateway_ip')
        sec_gateway = subnet_dict.get('secondary_gw')
        return {'subnet': subnet, 'start': start, 'end': end,
                'gateway': gateway, 'sec_gateway': sec_gateway}