In section 3.3.2 the book says (emphasis mine):

To demonstrate that just about any arbitrary traversal can be placed inside the by modulator here
is one more example that counts the number of outgoing routes for the source and destination
airports as part of generating the path result.

g.V(3).out().limit(5).path().by(out().count().fold())

As I understand it (so far), out().count().fold() is not a traversal because it does not start with g.V() or g.E(). Used on its own, out().count().fold() produces only [0]. Or is any syntactically valid sequence of steps a traversal?

Would it be correct to say that such an inner (my term) or embedded traversal takes its input from the outer traversal up to the position of the embedded traversal?