return vertex
	}
	return g.createVertex_locked(vertexType, namespace, name)
}

// must be called under a read lock
func (g *Graph) getVertex_rlocked(vertexType vertexType, namespace, name string) (*namedVertex, bool) {
	vertex, exists := g.vertices[vertexType][namespace][name]
	return vertex, exists
}

// must be called under a write lock