anchor.diff:  * A SPARQL Union query with un-balanced patterns, i.e. a gremlin union traversal can only be generated if the input
   SPARQL query has the same number of patterns on both the side of the union operator. For instance, the following
   SPARQL query cannot be mapped using Gremlinator, since a union is executed between different number of graph patterns
  -(two patterns _union_ 1 pattern).
  +(two patterns `union` 1 pattern).
   
   [source,groovy]
   ----
  
positive.code: 
  == SPARQL-Gremlin
  
  image:https://raw.githubusercontent.com/LITMUS-Benchmark-Suite/sparql-to-gremlin/master/docs/images/sparql-gremlin-logo.png[gremlinator]
  
  The SPARQL-Gremlin transpiler, transforms link:https://en.wikipedia.org/wiki/SPARQL[SPARQL] queries into Gremlin traversals. It is based on the  https://jena.apache.org/index.html[Apache Jena] SPARQL processor https://jena.apache.org/documentation/query/index.html[ARQ], which provides access to a syntax tree of a SPARQL query.
  
  
  The goal of this work is to bridge the query interoperability gap between the two famous, yet fairly disconnected, graph communities: Semantic Web (which relies on the RDF data model) and Graph database
  (which relies on Property graph data model).
  
  NOTE: The foundational research work on SPARQL-Gremlin transpiler (aka Gremlinator) can be found from -
  https://arxiv.org/pdf/1801.02911.pdf[Gremlinator full paper]. In this
  paper, we present and discuss the notion of graph query language
  semantics of SPARQL and Gremlin, and a formal mapping between SPARQL
  pattern matching graph patterns and Gremlin traversals. Furthermore, we
  point the interested reader to the following resourcesfor a better
  understanding: (1) Gremlinator demonstration -
  (http://gremlinator.iai.uni-bonn.de:8080/Demo/[Public Demo Mirror 1])
  and (http://195.201.31.31:8080/Demo/[Public Demo Mirror 2]); (2) A short video tutorial on how to use the demonstration - https://www.youtube.com/watch?v=Z0ETx2IBamw[here]
  
  [source,xml]
  ----
  
negative.code: [[supported-queries]]
  === Supported Queries
  
  The SPARQL-Gremlin transpiler currently supports translation of the SPARQL 1.0 specification, especially `SELECT`
  queries, though there is an on-going effort to cover the entire SPARQL 1.1 query feature spectrum. The supported
  SPARQL query types are:
  
  * Union 
  * Optional 
  