code: func (c *Client) HasPlugin(name string) (bool, error) {
  	plugins, err := c.Plugins()
  	if err != nil {
  		return false, nil
  	}
  	for _, plugin := range plugins {
  		if plugin == name {
  			return true, nil
  		}
  	}
  	return false, nil
  }
docs: // HasPlugin indicates whether the cluster has the named plugin.