当前文件的第一行插入一条数据，如csv文件插入一行列名
定义如下函数即可：

    def _write_raw_index(path, text):
        """在csv文件中第一行添加索引字段"""
        with open(path, 'r+', encoding='utf-8') as f:
            content = f.read()
            f.seek(0, 0)
            f.write(text + '\n' + content)

if __name__ == '__main__':
	result = 'test.csv'
	index_text = 'index,col1,col2'
	_write_raw_index(path=result_path,text=index_text)