function tryConsumeDeclare() {
            var token = scanner.getToken();
            if (token === 122 /* DeclareKeyword */) {
                // declare module "mod"
                token = scanner.scan();
                if (token === 125 /* ModuleKeyword */) {
                    token = scanner.scan();
                    if (token === 9 /* StringLiteral */) {
                        recordAmbientExternalModule();
                    }
                }
                return true;
            }
            return false;
        }
Returns true if at least one token was consumed from the stream