The Missed Gift

Ten set() calls land on key "foo". Reveal them one at a time or all at once. Before we search anything, we want to notice a property of the resulting list.

set("foo", 1, "a")
set("foo", 4, "b")
set("foo", 7, "c")
set("foo", 10, "d")
set("foo", 15, "e")
set("foo", 22, "f")
set("foo", 28, "g")
set("foo", 33, "h")
set("foo", 40, "i")
set("foo", 47, "j")