gremlin-python lambdas do not work with HaltedTraverserStrategy(DetachedFactory)

When using the HaltedTraverserStrategy(o.a.t.g.s.u.d.DetachedFactory) in gremlin-python, lambdas cannot be processed, returning a Python NameError.

Using the examples from the documentation, against gremlin-server-modern-py.yaml

 g.V().out().map(lambda: "x: len(x.get().value('name'))").sum().toList()
[24L]

g.withStrategies(HaltedTraverserStrategy("org.apache.tinkerpop.gremlin.structure.util.detached.DetachedFactory")).V().out().map(lambda: "x: len(x.get().value('name'))").sum().toList()
GremlinServerError: 599: NameError: name 'TraversalStrategy' is not defined in <script> at line number 1