File                Read by      Returned by
-----------------   -----------  -----------
line                1st call(*)  scrapped
line                1st call(*)  scrapped
timestamped line    1st call(*)  1st call
line                1st call     1st call
line                1st call     1st call
timestamped line    1st call     2nd call
line                2nd call     2nd call
line                2nd call     2nd call
timestamped line    2nd call     3rd call
line                3rd call     3rd call
line                3rd call     3rd call
timestamped line    3rd call     4th call
EOF                 4th call     5th call