### test1.csv ###
1  aaa  ignored_field
3  ccc ignored_field
4  ddd ignored_field

### test2.csv ###
11 aaa ignored_field
22 bbb ignored_field
44 ddd   ignored_field

### test3.csv ###
333 ccc ignored_field
555 eee ignored_field
666  fff   ignored_field
777  ggg   ignored_field