def compact_tube_names(tube_names)
      tube_names = tube_names.first if tube_names && tube_names.size == 1 && tube_names.first.is_a?(Array)
      tube_names = Array(tube_names).compact if tube_names && Array(tube_names).compact.size > 0
      tube_names = nil if tube_names && tube_names.compact.empty?
      tube_names ||= Backburner.default_queues.any? ? Backburner.default_queues : all_existing_queues
      Array(tube_names).uniq
    end
Normalizes tube names given array of tube_names
Compacts nil items, flattens arrays, sets tubes to nil if no valid names
Loads default tubes when no tubes given.