anchor.diff:   .. Everything required of OTLP is required of OLAP (but not vice versa).
    .. GraphComputer API: `GraphComputer`, `Messenger`, `Memory`.
   
  -A collection of implementation notes:
  +Please consider the following implementation notes:
   
   * Be sure your `Graph` implementation is named as `XXXGraph` (e.g. TinkerGraph, Neo4jGraph, HadoopGraph, etc.).
   * Use `StringHelper` to ensuring that the `toString()` representation of classes are consistent with other implementations.
  
positive.code: 
  <1> Note that the final results of the reducer are provided to the Memory as specified by the application developer's `MapReduce.addSideEffectToMemory()` implementation.
  <2> If there is no reduce stage, the the map-stage results are inserted into Memory as specified by the application developer's `MapReduce.addSideEffectToMemory()` implementation.
  
  [[validating-with-gremlin-test]]
  Validating with Gremlin-Test
  
negative.code: * Use the numerous static method helper classes such as `ElementHelper`, `GraphComputerHelper`, `VertexProgramHelper`, etc.
  * There are a number of default methods on the provided interfaces that are semantically correct. However, if they are not efficient for the implementation, override them.
  * Implement the `structure/` package interfaces first and then, if desired, interfaces in the `process/` package interfaces.
  
  [[oltp-implementations]]
  OLTP Implementations
  