question: get the total number of documents in the corpus . concode_field_sep DocLengthStore DOCLENGTHSTORE concode_elem_sep IndexReader INDEXREADER concode_field_sep long getSumOfFieldLengths concode_elem_sep int getInternalDocid concode_elem_sep String getAttribute concode_elem_sep String getExternalDocid concode_elem_sep int getDocCount concode_elem_sep void initialize concode_elem_sep int getFieldLength
target: long function ( ) { return Idx . INDEXREADER . numDocs ( ) ; }