c.name = name
	c.handler = fn
	c.replace = true
	c.processor.callbacks = append(c.processor.callbacks, c)
	return c.processor.compile()
}

// getRIndex get right index from string slice
func getRIndex(strs []string, str string) int {
	for i := len(strs) - 1; i >= 0; i-- {
		if strs[i] == str {
			return i
		}
	}
	return -1
}