anchor.diff:  [gremlin-groovy,existing]
   ----
   input = ['A','B','D']
  -g.V().has('name', input.head()).
  +g.V(input.head()).
     repeat(out('hasParent')).emit().as('x').                               <1>
  -  V().has('name', within(input.tail())).                                 <2>
  +  V().has(id, within(input.tail())).                                     <2>
     repeat(out('hasParent')).emit(where(eq('x'))).                         <3>
     group().
       by(select('x')).
  
positive.code:   unfold().filter(select(values).count(local).is(input.tail().size())).
    order().
      by(select(values).unfold().sum()).
    select(keys).limit(1).valueMap(true)
  ----
  
  <1> The main difference for OLAP is the use of `aggregate()` over the mid-traversal`V()`.
  
negative.code: 
  [gremlin-groovy]
  ----
  g.addV(id, 'A').as('a').
    addV(id, 'B').as('b').
    addV(id, 'C').as('c').
    addV(id, 'D').as('d').
    addV(id, 'E').as('e').
    addV(id, 'F').as('f').
    addV(id, 'G').as('g').
    addE('hasParent').from('a').to('b').
    addE('hasParent').from('b').to('c').
    addE('hasParent').from('d').to('c').
  