default KeyValueSnapshot<K, V> snapshot(K from, K to) {
    throw new UnsupportedOperationException("snapshot() is not supported in " + this.getClass().getName());
  }
Returns a snapshot of this store for a sorted range of entries specified by [{@code from}, {@code to}).
The snapshot is immutable - ie., any mutations to the store are not reflected in the snapshot after it is created.

<p><b>API Note:</b> The returned snapshot MUST be closed after use.
@param from the key specifying the low endpoint (inclusive) of the keys in the returned range.
@param to the key specifying the high endpoint (exclusive) of the keys in the returned range.
@return a snapshot for the specified key range.
@throws NullPointerException if null is used for {@code from} or {@code to}.
samza-api/src/main/java/org/apache/samza/storage/kv/KeyValueStore.java