def unknown(message = nil, ex = nil, data = nil, &block)
      args = block ? yield : [message, ex, data]
      append(UNKNOWN, args)
    end
def unknown(message = nil, ex = nil, data = nil, &block)
      args = block ? yield : [message, ex, data]
      append(UNKNOWN, args)
    end
Log any one or more of a message, an exception and structured data as UNKNOWN.
 @return [Boolean] true
 @see Logging#debug