#4 Jaccard.score() returns NaN if both strings empty
open
nobody
None
5
2009-04-08
2009-04-08
Anonymous
No
Jaccard.score(s1, s2) returns NaN if both strings have zero tokens. this happens when both strings are empty, or the tokenizer doesn't find any tokens (NGram tokenizer with minNGramSize > size of the string)