(grow-two-files) begin
(grow-two-files) create "a"
(grow-two-files) create "b"
(grow-two-files) open "a"
(grow-two-files) open "b"
(grow-two-files) write "a" and "b" alternately
(grow-two-files) close "a"
(grow-two-files) close "b"
(grow-two-files) open "a" for verification
(grow-two-files) close "a"
(grow-two-files) open "b" for verification
(grow-two-files) close "b"
(grow-two-files) end