/**
 * Read an identifier, producing either a name token or matching on one of the existing keywords.
 * For performance, we pre-generate big decision tree that we traverse. Each node represents a
 * prefix and has 27 values, where the first value is the token or contextual token, if any (-1 if
 * not), and the other 26 values are the transitions to other nodes, or -1 to stop.
 */
export default function readWord(): void;