code: func Copy(dst, src interface{}) {
  	switch dst := dst.(type) {
  	case *types.Any:
  		src := src.(*types.Any)
  		dst.TypeUrl = src.TypeUrl
  		if src.Value != nil {
  			dst.Value = make([]byte, len(src.Value))
  			copy(dst.Value, src.Value)
  		} else {
  			dst.Value = nil
  		}
  	case *types.Duration:
  		src := src.(*types.Duration)
  		*dst = *src
  	case *time.Duration:
  		src := src.(*time.Duration)
  		*dst = *src
  	case *types.Timestamp:
  		src := src.(*types.Timestamp)
  		*dst = *src
  	case *types.BoolValue:
  		src := src.(*types.BoolValue)
  		*dst = *src
  	case *types.Int64Value:
  		src := src.(*types.Int64Value)
  		*dst = *src
  	case CopierFrom:
  		dst.CopyFrom(src)
  	default:
  		panic(fmt.Sprintf("Copy for %T not implemented", dst))
  	}
  
  }
docs: // Copy copies src into dst. dst and src must have the same type.
  //
  // If the type has a copy function defined, it will be used.
  //
  // Default implementations for builtin types and well known protobuf types may
  // be provided.
  //
  // If the copy cannot be performed, this function will panic. Make sure to test
  // types that use this function.