The nodes all extend the interface {@link polyglot.ast.Node Node}. Each node has accessor methods and methods to implement passes over the node. The setter methods are non-destructive: they create a copy of the node and return the copy. The traversal interface is defined in {@link polyglot.visit.NodeVisitor NodeVisitor}. Nodes are constructed using a {@link polyglot.ast.NodeFactory NodeFactory}. @see polyglot.ast.Node @see polyglot.visit.NodeVisitor @see polyglot.ast.NodeFactory