website/playground/buttons.js/ClipboardButton/render
class ClipboardButton:  render() {
    const { children, copy, ...rest } = this.props;
    const { showTooltip, tooltipText } = this.state;

    return (
      <Button ref={this.ref} {...rest}>
        {showTooltip ? <span className="tooltip">{tooltipText}</span> : null}
        {children}
      </Button>
    );
  }