@Override
        protected Map<String, Object> initialValue() {
            return new HashMap<>();
        }
Name of variable that holds local variables to be globally bound if "interpreter mode" is enabled with
{@link InterpreterModeGroovyCustomizer}.
gremlin-groovy/src/main/java/org/apache/tinkerpop/gremlin/groovy/jsr223/GremlinGroovyScriptEngine.java