We create factory functions, node and rel, that instantiate the elements of a single property graph. github 
Nodes and Rels have type and props. Both can be retrieved by index into the nodes and rels arrays.
nodes: [{type, in, out, props}, ...] rels: [{type, from, to, props}, ...]
Nodes have in and out arrays that list directional relations pointing into or out of the node.
Rels have from and to properties that identify the nodes that they directionally connect.
//wiki.ralfbarkow.ch/assets/pages/mock-graph-data/transform.html HEIGHT 300