Step - and

and(a, b, ...) keeps a traverser when every child traversal produces a result for it.

g.V().and(__.outE("knows"), __.values("age").is(P.lt(30))).values("name")   // ["marko"]

The infix form a.and().b

and() with no argument is TinkerPop's infix notation, rewritten as TinkerPop's ConnectiveStrategy does before the traversal runs:

• the left operand is every step before and(), back to the start of the traversal; the start step of the root traversal (V(), E(), inject(), ...) and the step labels it carries stay outside;
• the right operand is every step after and() up to the end of the traversal; a further and() starts another operand (a.and().b.and().c is and(a, b, c));
• and() binds tighter than or(): a.and().b.or().c is or(and(a, b), c).

g.V().where(__.out("created").and().out("knows").or().in("knows")).values("name")
// ["marko", "vadas", "josh"]
g.V().has("name", "marko").and().has("age", 29)              // v[1]

Because the right operand runs to the end, a step written after the infix form is part of it: g.V().has("name", "marko").and().has("age", 29).values("name") still yields the vertex, with values("name") inside the and(). Wrap the connective in a child traversal (filter(__.has(..).and().has(..)), where(..)) to continue after it.

Rust: the prefix form and(vec![a, b]); the infix form is a DSL notation.