code: def Phylesystem(repos_dict=None,
                  repos_par=None,
                  with_caching=True,
                  repo_nexml2json=None,
                  git_ssh=None,
                  pkey=None,
                  git_action_class=PhylesystemGitAction,
                  mirror_info=None,
                  new_study_prefix=None,
                  infrastructure_commit_author='OpenTree API <api@opentreeoflife.org>'):
      
      if not repo_nexml2json:
          repo_nexml2json = get_config_setting('phylesystem', 'repo_nexml2json')
      global _THE_PHYLESYSTEM
      if _THE_PHYLESYSTEM is None:
          _THE_PHYLESYSTEM = _Phylesystem(repos_dict=repos_dict,
                                          repos_par=repos_par,
                                          with_caching=with_caching,
                                          repo_nexml2json=repo_nexml2json,
                                          git_ssh=git_ssh,
                                          pkey=pkey,
                                          git_action_class=git_action_class,
                                          mirror_info=mirror_info,
                                          new_study_prefix=new_study_prefix,
                                          infrastructure_commit_author=infrastructure_commit_author)
      return _THE_PHYLESYSTEM
docs: Factory function for a _Phylesystem object.
  
      A wrapper around the _Phylesystem class instantiation for
      the most common use case: a singleton _Phylesystem.
      If you need distinct _Phylesystem objects, you'll need to
      call that class directly.