Function isCmcdV1Key

isCmcdV1Key(key: string): key is CmcdKey
Filter for CMCD version 1 keys.
Parameters
- key: string
  The CMCD key to filter.
Returns key is CmcdKey
true if the key should be included, false otherwise.
Example
```
equal(isCmcdV1Key('br'), true)
equal(isCmcdV1Key('e'), false)
```
- Defined in isCmcdV1Key.ts:19