You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: filter.go
    path of file: ./repos/minio/internal/bucket/replication
    
    the code of the file until where you have to start completion: // Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation
    
func (f Filter) Validate() error {
	// A Filter must have exactly one of Prefix, Tag, or And specified.
	if !f.And.isEmpty() {
		if f.Prefix != "" {
			return errInvalidFilter
		}
		if !f.Tag.IsEmpty() {
			return errInvalidFilter
		}
		if err := f.And.Validate(); err != nil {
			return err
		}
	}
	if f.Prefix != "" {
		if !f.Tag.IsEmpty() {
			return errInvalidFilter
		}
	}
	if !f.Tag.IsEmpty() {
		if err := f.Tag.Validate(); err != nil {
			return err
		}
	}
	return nil
}