This method counts the number of vertex records.
On occasion you may find it useful to retrieve or reference the number of records in a database. Using this method, you can count the number of vertex records in a database. By default, it returns the records for the vertex base class
V. You can retrieve a count of records in subclasses of
V by passing the class name as an argument.
var count = db.countVertices(<class>)
<class>Defines the class you want to count. Defaults to the base edge class,