GetNeighbors returns all direct neighbors of the given item.

NewVertex constructs a Vertex.

Sort performs a topological sort on the given data collections, so that the items can be inserted into a persistent store to minimize the risk of evaluating a flag before its prerequisites/segments have been stored.

Vertex represents a particular data item, identified by kind + key.

AdjacencyList is a map of vertices (kind/key) to neighbors (dependencies).

Neighbors is a set of vertices.