aa	11
bb	22
cc	33
dd	44

=== dl.1

aa

• a
• b

bb

• a
• b

cc

• a
• b

dd

• a
• b

=== dl.2

aa

ab

bb

ab

cc

ab

dd

ab

=== foreach.1 1:aa -> a 1:aa -> b 2:bb -> a 2:bb -> b 3:cc -> a 3:cc -> b 4:dd -> a 4:dd -> b . === foreach.2 1:aa -> a 2:aa -> b 3:bb -> a 4:bb -> b 5:cc -> a 6:cc -> b 7:dd -> a 8:dd -> b