code: func SolrUpdateString(c *Connection, commit bool) string {
  	s := fmt.Sprintf("%s/update", c.URL)
  	if commit {
  		return fmt.Sprintf("%s?commit=true", s)
  	}
  	return s
  }
docs: /*
   * Generates a Solr update query string. Adds ?commit=true
   * if commit arg is true.
   */