introduction to pytorch listing - extracting values from tensor using the gather method in [ ] torch rand( , in [ ] out[ ]tensor([[ ][ ][ ][ ]]in [ ] shape out[ ]torch size([ ]in [ ] torch longtensor([[ , , , ]]in [ ] out[ ]tensor([[ ]]in [ ] shape out[ ]torch size([ ]in [ ] gather( ,bin [ ] out[ ]tensor([[ ]]in [ ] shape out[ ]torch size([ ]in [ ] torch longtensor([[ ],[ ],[ ],[ ]]in [ ] out[ ]