The `@cached` decorator on `KeyStore._get_server_verify_key` was missing its `num_args` parameter, which meant that it was returning the wrong key for any server which had more than one recorded key. By way of a fix, change the default for `num_args` to be *all* arguments. To implement that, factor out a common base class for `CacheDescriptor` and `CacheListDescriptor`.  | 
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|---|---|---|
| .. | ||
| __init__.py | ||
| descriptors.py | ||
| dictionary_cache.py | ||
| expiringcache.py | ||
| lrucache.py | ||
| response_cache.py | ||
| snapshot_cache.py | ||
| stream_change_cache.py | ||
| treecache.py | ||