tokens: So because the == function for comparing optionals requires a String ? argument , " John " will be implicitly converted to { Some " John " } , allowing the == operator between two optionals to be used .
ner_tags: O O O B-Code_Block O O O B-Data_Type O O B-Data_Type I-Data_Type O O B-Value I-Value I-Value O O O O O B-Code_Block I-Code_Block I-Code_Block I-Code_Block I-Code_Block I-Code_Block O O O B-Code_Block O O O B-Data_Type O O O O