Unicode equal comparison failed to convert both arguments to Unicode

[lx2pwnd]

I have a problem when i run a query with py2neo:

posts = graph.run(
            'MATCH (p:Post) WHERE p.post CONTAINS \'' + keyword + '\' '
            'AND p.timestamp>' + str(startDate) +
            ' AND p.timestamp<' + str(endDate) +
            ' return p').data()
print json.dumps(posts)

It works perfectly, but when the keyword is a word which contains a latin letter (like giovedì), I have this error 'Unicode equal comparison failed to convert both arguments to Unicode'. However, if I use another word which doesn't have any latin letter in the same p.Post, I don't get any error. Why ?

I have tried to use match.where() function to bypass this warning, but I don't understand how to use multiple clauses where:

list(match("Post").where(post__contains=keyword, timestamp__gt=startDate, timestamp__lt=endDate))

But it doesn't print anything