`topological-sort``DAG``PRED`procedureSorts the directed acyclic graph dag

`DAG`so that for every edge from vertex u to v, u will come before v in the resulting list of vertices.`DAG`is a list of sublists. The car of each sublist is a vertex. The cdr is the adjacency list of that vertex, i.e. a list of all vertices to which there exists an edge from the car vertex.`pred`is procedure of two arguments that should compare vertices for equality.Time complexity: O (|V| + |E|)

(topological-sort '((shirt tie belt) (tie jacket) (belt jacket) (watch) (pants shoes belt) (undershorts pants shoes) (socks shoes)) eq?) => (socks undershorts pants shoes watch shirt belt tie jacket)

If a cycle is detected during the sorting process, an exception of the condition kinds

`(exn runtime cycle)`is thrown.