anchor.diff:  assert optionArg.file.equals("output.txt");
   ----
   
  -Programmatically set separators are only used when parsing.
  -Changing the value does not modify the usage help message.
   
   === Subclassing for Reuse
   Picocli will walk the class hierarchy to check for annotations, so you can declare common @Options and @Command attributes on a superclass and override these fields or attributes on a subclass.
  
positive.code: @Command(separator = " ")
  ----
  
  NOTE: the `@Command(separator = " ")` annotation also affects how picocli parses the command line. If you want the command parser to recognize one separator (`=` for example), but display a different separator (a space for example) in the usage help message, you need to programmatically configure the parser with the `CommandLine.setSeparator` method. See <<Custom Separators>>.
  
  === Hidden Options and Parameters
  Options and Parameters with the `hidden` attribute set to `true` will not be shown in the usage help message.
  
negative.code: assert optionArg.file.equals("output.txt");
  ----
  
  
  Alternatively, the separator string can be changed programmatically with the `CommandLine.setSeparator(String separator)` method.
  For example:
  