Interface NodeVisitor

A function that walks a node using the given visitor, lifting node arrays into single nodes, returning an node which satisfies the test.

• If the input node is undefined, then the output is undefined.
• If the visitor returns undefined, then the output is undefined.
• If the output node is not undefined, then it will satisfy the test function.
• In order to obtain a return type that is more specific than Node, a test function must be provided, and that function must be a type predicate.

For the canonical implementation of this type,