code: func (api *Client) CreateChildGroup(group string) (*Group, error) {
  	return api.CreateChildGroupContext(context.Background(), group)
  }
docs: // CreateChildGroup creates a new private group archiving the old one
  // This method takes an existing private group and performs the following steps:
  //   1. Renames the existing group (from "example" to "example-archived").
  //   2. Archives the existing group.
  //   3. Creates a new group with the name of the existing group.
  //   4. Adds all members of the existing group to the new group.