private static GraphTraversal<?, ?> transform(final E_LogicalOr expression) {
        return __.or(
                transform(expression.getArg1()),
                transform(expression.getArg2()));
    }
Converts a general {@code Expr} to an anonymous {@link GraphTraversal}.
sparql-gremlin/src/main/java/org/apache/tinkerpop/gremlin/sparql/WhereTraversalBuilder.java