code: func Init(ic ipamapi.Callback, l, g interface{}) error {
  	var (
  		ok                bool
  		localDs, globalDs datastore.DataStore
  	)
  
  	if l != nil {
  		if localDs, ok = l.(datastore.DataStore); !ok {
  			return errors.New("incorrect local datastore passed to built-in ipam init")
  		}
  	}
  
  	if g != nil {
  		if globalDs, ok = g.(datastore.DataStore); !ok {
  			return errors.New("incorrect global datastore passed to built-in ipam init")
  		}
  	}
  
  	ipamutils.ConfigLocalScopeDefaultNetworks(GetDefaultIPAddressPool())
  
  	a, err := ipam.NewAllocator(localDs, globalDs)
  	if err != nil {
  		return err
  	}
  
  	cps := &ipamapi.Capability{RequiresRequestReplay: true}
  
  	return ic.RegisterIpamDriverWithCapabilities(ipamapi.DefaultIPAM, a, cps)
  }
docs: // Init registers the built-in ipam service with libnetwork