  We generalise the insertion into a binary heap to any directed acyclic graph
(DAG) with one source vertex. This lets us formulate a general method for
converting any such DAG into a data structure with priority queue interface. We
apply our method to a hypercube DAG to obtain a sorting algorithm of complexity
$\mathcal{O}(n\log^2 (n))$. As another curious application, we derive a
relationship between length of longest path and maximum degree of a vertex in a
DAG.
