```ts
export function tagOpen(marker: string): string {
  if (!marker.startsWith('<') || !marker.endsWith('>')) {
    throw new Error('Marker must be wrapped in angle brackets.');
  }
  const name = marker.slice(1, -1);
  return name;
}

export function tagPair(opening: string, closing: string): boolean {
  return opening === closing;
}
```