code: function graphFromStatements (rdf, statements) {
    let graph = rdf.graph()
  
    statements.forEach((st) => { graph.addStatement(st) })
  
    return graph
  }
docs: Converts a list of RDF statements into a Graph, and returns
  it.
  @method graphFromStatements
  
  @param rdf {RDF} RDF library such as rdflib.js
  @param statements {Array<Statement>}
  
  @return {Graph}