I think it's a good idea adding a keyword argument to specify the separator of readlines().

I believe most people can accept the universal meaning of "line", which has similar meaning of "record", that is a chunk data, maybe from using line separators other than '\n' in perl, or akw, or the find command. Maybe doing this doesn't pollute the meaning of "readlines". Splitting the file contents with s special character is really a common usage. Besides, I feel using a line separator other than '\n' doesn't mean we're dealing with binary format, in fact, I often deal with text format with the record separator '\t'.