anchor.diff:  g.V(v).properties().property('creator','stephen')
   g.V(v).properties().properties()
   g.V(v).properties('name').valueMap()
  -g.V(v).property(single, 'name','okram') <6>
  +g.V(v).property('name','okram') <6>
   g.V(v).properties('name')
   g.V(v).values('name') <7>
   ----
  
positive.code:       outV().as('b').
        select().by('skill').by('name') // rank the users of gremlin by their skill level
  ----
  
  Graph Variables
  ---------------
  
negative.code: <3> Vertex property removal is identical to property removal.
  <4> It is property to get the properties of a vertex property.
  <5> A vertex property can have any number of key/value properties attached to it.
  <6> `property(...)` will remove all existing key'd properties before adding the new single property (see `VertexProperty.Cardinality`).
  <7> If only the value of a property is needed, then `values()` can be used.
  
  If the concept of vertex properties is difficult to grasp, then it may be best to think of vertex properties in terms of "literal vertices." A vertex can have an edge to a "literal vertex" that has a single value key/value -- e.g. "value=okram." The edge that points to that literal vertex has an edge-label of "name." The properties on the edge represent the literal vertex's properties. The "literal vertex" can not have any other edges to it (only one from the associated vertex).
  