    graph.getNeighbors(element [, opt])

Get all the neighbors of `element` in the graph. Neighbors are all the elements connected to `element` via either an inbound or an outbound link.

Accepts several options, which may be provided inside an `opt` object:

- `deep` - also return all the neighbors of all the elements embedded inside `element`.
- `inbound` - return only inbound neighbors (neighbors connected with a link whose `target` is the `element`).
- `outbound` - return only outbound neighbors (neighbors connected with a link whose `source` is the `element`).
- `indirect` - in addition to standard rules (including `deep`/`outbound`/`inbound` modifications), also return the elements that can only be considered neighbors of `element` if we go against the flow of directed links at link-link connections.