从文件中读出的一个汉字字符串
用这个句话判断是否包含回车：

python    if '\n' in mystring:
        print type(mystring)
        #<type 'unicode'>
        mystring.replace('\n', '')
        #does not work
        mystring.replace(u'\n', u'')
        #does not work
        mystring.encode("gbk")
        mystring.replace("\n", "")
        #does not work
        mystring.encode("utf-8")
        mystring.replace("\n", "")
        #does not work
        mystring.encode("ascii")
        mystring.replace("\n", "")
        #UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-20
        print mystring

这该如何是好？请指教！