code: func (r *DrvRegistry) IPAMDefaultAddressSpaces(name string) (string, string, error) {
  	r.Lock()
  	defer r.Unlock()
  
  	i, ok := r.ipamDrivers[name]
  	if !ok {
  		return "", "", fmt.Errorf("ipam %s not found", name)
  	}
  
  	return i.defaultLocalAddressSpace, i.defaultGlobalAddressSpace, nil
  }
docs: // IPAMDefaultAddressSpaces returns the default address space strings for the passed IPAM driver name.