anchor.diff:  * SPARQL queries with variables in the predicate position are not currently covered, with an exception of the following
   case:
   
  -[source,groovy]
  +[source,text]
   ----
   g.sparql("""SELECT * WHERE { ?x ?y ?z . }""")
   ----
  
positive.code: 
  [source,groovy]
  ----
  g.sparql("""SELECT COUNT(?project) 
  WHERE {
    ?person v:label "person" .
    ?person v:age ?age . FILTER (?age < 30)
  
negative.code: 
  [gremlin-groovy,existing]
  ----
  g.sparql("""SELECT ?age ?name
  WHERE {
    ?person v:label "person" .
    ?person v:age ?age .
    ?person v:name ?name .
  } ORDER BY (?age))
  ----
  
  [[group-by]]
  