tokens: Here 's an example : if you write your own Numeric class ( say , a Quaternion class ) , then the system builtin Fixnum class does n't know anything about Quaternions . So , when you ask the Fixnum 0 whether it is equal to the Quaternion ( 0 , 0 , 0 , 0 ) , it will responds false , even though that 's wrong .
ner_tags: O O O O O O O O O O B-Class O O O O O B-Class O O O O O O O B-Class O O O O O O B-Class O O O O O O O B-Class O O O O O O O B-Class B-Value I-Value I-Value I-Value I-Value I-Value I-Value I-Value I-Value O O O O B-Value O O O O O O O