docs: def init_argparser(self, argparser):
          """
          Other runtimes (or users of ArgumentParser) can pass their
          subparser into here to collect the arguments here for a
          subcommand.
          """
  
          super(ToolchainRuntime, self).init_argparser(argparser)
  
          # it is possible for subclasses to fully override this, but if
          # they are using this as the runtime to drive the toolchain they
          # should be prepared to follow the layout, but if they omit them
          # it should only result in the spec omitting these arguments.
          self.init_argparser_export_target(argparser)
          self.init_argparser_working_dir(argparser)
          self.init_argparser_build_dir(argparser)
          self.init_argparser_optional_advice(argparser)