def del(digest: nil, pattern: nil, count: DEFAULT_COUNT)
      return delete_by_pattern(pattern, count: count) if pattern
      return delete_by_digest(digest) if digest

      raise ArgumentError, "either digest or pattern need to be provided"
    end
def del(digest: nil, pattern: nil, count: DEFAULT_COUNT)
      return delete_by_pattern(pattern, count: count) if pattern
      return delete_by_digest(digest) if digest

      raise ArgumentError, "either digest or pattern need to be provided"
    end
Deletes unique digest either by a digest or pattern

 @param [String] digest the full digest to delete
 @param [String] pattern a key pattern to match with
 @param [Integer] count the maximum number
 @raise [ArgumentError] when both pattern and digest are nil
 @return [Array<String>] with unique digests