arangosh> var examples = require("org/arangodb/graph-examples/example-graph.js");
arangosh> var graph = examples.loadGraph("social");
arangosh> graph.relation.save("relation/aliceAndBob", "female/alice", {type: "married", _key: "bobAndAlice"});
[ArangoError 1906: invalid edge between relation/aliceAndBob and female/alice.]