ame, and option's value.
	If the function returns a value then the options processing fails and the returned value is used as error message.</li>
</ul>

<h2>Examples</h2>

<h3><a name="CommandLineServer">Server with Command-Line Options</a></h3>

<pre>
local Arguments = require "loop.compiler.Arguments"
local Verbose   = require "loop.debug.Verbose"

local verbose = Verbose()

local args = Arguments{
  _optpat = "^%-%-(%w+)([=:]?)(.-)$"
  port = 0
  verb = {}
}
function args:log(optname, optvalue)
  local f