Using the difflib.HtmlDiff class - showing single chars

I am using the difflib.HtmlDiff class, calling the function using two sets of text (HTML from websites), however when it makes the table

html_diff = difflib.HtmlDiff()
print html_diff.make_table(previous_contents, fetch_url.page_contents)

however that just seems to compare char by char (1 char per table row), and I end up with a 4.3MB txt file for two sets of html which are only 100k.

The doc file says,

Compares fromlines and tolines (lists of strings) and returns a string开发者_StackOverflow社区 which is a 
complete HTML file containing a table showing line by line differences with 
inter-line and intra-line changes highlighted.

however that doesn't seem to be the case.

Any suggestions?

You're supplying strings, not lists of strings (lines).

Assuming UNIX or Windows line ends:

print html_diff.make_table(previous_contents.split('\n'),
                           fetch_url.page_contents.split('\n'))