class Asset

def self.thumbnail_options
  asset_sizes = thumbnail_sizes.collect{|k,v|
    size_id = k
    size_description = "#{k}: "
    size_description << (v.is_a?(Array) ? v.join(' as ') : v)
    [size_description, size_id]
  }.sort_by{|pair| pair.last.to_s}
  asset_sizes.unshift ['Original (as uploaded)', 'original']
  asset_sizes
end