Function withHistory

Emits the upstream value as the first element in an array, followed by the last count values in reverse chronological order.

source:         -1----2------3--------4--------5--------|
withHistory(2): -[1]--[2,1]--[3,2,1]--[4,3,2]--[5,4,3]--|
withHistory(0): -[1]--[2]----[3]------[4]------[5]------|
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