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: column.go
    path of file: ./repos/tidb/pkg/util/column-mapping
    
    the code of the file until where you have to start completion: // Copyright 2022 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use thi
    
func (r *Rule) adjustColumnPosition(source, target int) (src int, targ int, err error) {
	// if not found target, ignore it
	if target == -1 {
		return source, target, errors.NotFoundf("target column %s", r.TargetColumn)
	}

	return source, target, nil
}