python脚本如何自动生成文件

 def produceBnf(infilename,outfilename):
    List=[]
    with open(infilename,'r') as inf:
        for line in inf.readlines():
            List.append(re.match("正则表达式").group(?))
    with open(outfilename,'w') as outf:
        i=0
        outf.write("文件头");
        for command in List:
                outf.write(“写入刚刚读取的内容（也可能是某种对应关系）”)
                outf.write("写入其他内容")
        outf.write("写入文件尾")