module Middleman::Assets

def self.before(position, *args)
  current_index = @@asset_handler_map.index(position)
  return nil unless current_index
  previous = current_index - 1
  if (previous >= 0) && (previous < @@asset_handler_map.length)
    @@asset_handler_stack[previous].call(*args)
  else
    nil
  end
end