Does Whoosh Require All Strings To Be Unicode?

I am redoing my search app in Whoosh from Solr. I am now learning from the quick start. But I kept running into problems each time I had to deal with strings >>>writer.add

Solution 1:

Yes, it requires strings are in Unicode.

 query = QueryParser("content", ix.schema).parse("first")

Change that to:

query = QueryParser("content", ix.schema).parse(u"first")