walk a directed acyclic graph
walk a directed acyclic graph, given a key function, comparison function, find function, and a next function.
var walk = dag'HASH1' 'HASH2' key find cmp nextwalknull// data === if no more items
dag([key list], key_function, find_function, comparison_function, next_function) -> fn(close, ready)
create a dag walker using the following definitions: