code: def ivy(self, bootstrap_workunit_factory=None):
      
      return Ivy(self._get_classpath(bootstrap_workunit_factory),
                 ivy_settings=self._ivy_subsystem.get_options().ivy_settings,
                 ivy_resolution_cache_dir=self._ivy_subsystem.resolution_cache_dir(),
                 extra_jvm_options=self._ivy_subsystem.extra_jvm_options())
docs: Returns an ivy instance bootstrapped by this bootstrapper.
  
      :param bootstrap_workunit_factory: the optional workunit to bootstrap under.
      :raises: Bootstrapper.Error if ivy could not be bootstrapped