@brief Get the amount of vertices of the graph that share common properties.

`graph._countCommonProperties(vertex1Example, vertex2Examples, options)`

Similar to [_commonProperties](#commonproperties) but returns count instead of
the objects.

@EXAMPLES

A route planner example, all locations with the same properties:

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleAmountProperties1}
var examples = require("@arangodb/graph-examples/example-graph.js");
var graph = examples.loadGraph("routeplanner");
graph._countCommonProperties({}, {});
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT

A route planner example, all German cities which share same properties except for population.

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleAmountProperties2}
var examples = require("@arangodb/graph-examples/example-graph.js");
var graph = examples.loadGraph("routeplanner");
| graph._countCommonProperties({}, {}, {vertex1CollectionRestriction : 'germanCity',
  vertex2CollectionRestriction : 'germanCity' ,ignoreProperties: 'population'});
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT