Defines the options you require for your program. You should pass if the options as a string array. There are two modifiers you can use to specify option arguments. Use "=" at the end of your option to specify that this option has to have an argument, and use =? at the end of your option to specify that an argument is optional.
GetOpt.SetOpts(new string[] {"a", "b", "foo=", "bar=?"})