question: public void index ( Iterator tuples , String field ) { while ( tuples . hasNext ( ) ) { Tuple t = ( Tuple ) tuples . next ( ) ; index ( t , field ) ; } }
target:  Indexes the data values for the given field name for each Tuple in the provided Iterator. These values are used to construct an internal data structure allowing fast searches over these attributes. To index multiple fields, simply call this method multiple times with the desired field names.