Hi all: I tried the one-line command in a interaction mode: [x for x in [1, 2, 3], y for y in [4, 5, 6]] and the result surprised me, that is: [[1,2,3],[1,2,3],[1,2,3],9,9,9] Who can explain the behavior? Since I expected the result should be: [[1,4],[1,5],[1,6],[2,4],...] -- Pary All Rough Yet. parywu at seed.net.tw