simplifyTag = tag => {
  for (const prefix of ['Alleged: ', 'DebugName: ']) {
    if (tag.startsWith(prefix)) {
      return tag.slice(prefix.length);
    }
  }
  return tag;
}
Return `tag` after stripping off any `'Alleged: '` or `'DebugName: '`
prefix if present.
```js
simplifyTag('Alleged: moola issuer') === 'moola issuer'
```
If there are multiple such prefixes, only the outer one is removed.

@param {string} tag
@returns {string}