code: func (c *Manager) CreateLibraryItem(ctx context.Context, item Item) (string, error) {
  	type createItemSpec struct {
  		Name        string `json:"name"`
  		Description string `json:"description"`
  		LibraryID   string `json:"library_id,omitempty"`
  		Type        string `json:"type"`
  	}
  	spec := struct {
  		Item createItemSpec `json:"create_spec"`
  	}{
  		Item: createItemSpec{
  			Name:        item.Name,
  			Description: item.Description,
  			LibraryID:   item.LibraryID,
  			Type:        item.Type,
  		},
  	}
  	url := internal.URL(c, internal.LibraryItemPath)
  	var res string
  	return res, c.Do(ctx, url.Request(http.MethodPost, spec), &res)
  }
docs: // CreateLibraryItem creates a new library item