# File lib/memcache.rb, line 153
  def add(key, value, opts = {})
    opts = compatible_opts(opts)
    key  = key.to_s
    backup.add(key, value, opts) if backup

    expiry = opts[:expiry] || default_expiry
    flags  = opts[:flags]  || 0
    data   = marshal(value, opts)
    server(key).add(key, data, expiry, flags) && value
  end