@brief Get all common neighbors of the vertices defined by the examples.

`graph._commonNeighbors(vertex1Example, vertex2Examples, optionsVertex1, optionsVertex2)`

This function returns the intersection of *graph_module._neighbors(vertex1Example, optionsVertex1)*
and *graph_module._neighbors(vertex2Example, optionsVertex2)*.
For parameter documentation see [_neighbors](#neighbors).

The complexity of this method is **O(n\*m^x)** with *n* being the maximal amount of vertices
defined by the parameters vertexExamples, *m* the average amount of neighbors and *x* the
maximal depths.
Hence the default call would have a complexity of **O(n\*m)**;

@EXAMPLES

A route planner example, all common neighbors of capitals.

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleCommonNeighbors1}
var examples = require("@arangodb/graph-examples/example-graph.js");
var graph = examples.loadGraph("routeplanner");
graph._commonNeighbors({isCapital : true}, {isCapital : true});
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT

A route planner example, all common outbound neighbors of Hamburg with any other location
which have a maximal depth of 2 :

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleCommonNeighbors2}
  var examples = require("@arangodb/graph-examples/example-graph.js");
  var graph = examples.loadGraph("routeplanner");
| graph._commonNeighbors(
|   'germanCity/Hamburg',
|   {},
|   {direction : 'outbound', maxDepth : 2},
    {direction : 'outbound', maxDepth : 2});
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT