How to use the pin.registry function in pin

def execute(self):
        if self.cwd == self.root:
            self.raise_exists()
        else:
            print "Creating .pin directory structure..."
            alias = None
            if self.options.alias:
                alias = self.options.alias[0]
            registry.initialize_project(self.cwd, alias=alias)
            self.root = self.cwd
            return True

return
            else:
                print "Alias `{alias}' already set.".format(alias=name)
                return
        else:
            current_alias = registry._projects[proj_path].get('alias')
            if current_alias:
                prompt =  "Alias `{alias}' already set, overwrite?".format(alias=current_alias)
                answer = option_select(['y','n'], prompt)
                if answer == 'n':
                    print "Aborted."
                    return
                
            _projects[proj_path]['alias'] = name
            _aliases[name] = proj_path
            registry.save_registry()
            print "Alias `{alias}' has been set for, {path}".format(alias=name,
                                                                    path=proj_path)
            return True

def activate_virtualenv(path):
    if path:
        path = os.path.join(path,
                            PROJECT_FOLDERNAME,
                            VIRTUALENV_FOLDERNAME)
        settings = os.path.join(registry.get_settings_path(), 'source.sh')
        with open(settings, 'w') as file:
            file.write("source %s\n" % os.path.join(path, "bin/activate"))

def execute(self):
#        pdb.set_trace()
        name = self.options.name
        project = getattr(self.options, 'project', None)
        if project:
            proj_path = registry.pathfor(project)
            if not proj_path:
                print "* Project", project, "not found."
                return
        elif self.root:
            proj_path = self.root
        else:
            print "Must provide -p/--project option, if outside of pin project."
            return
        if name in registry._aliases:
            if proj_path != registry._aliases[name]:
                print "Alias `{alias}' already exists for other project:".format(alias=name)
                print registry._aliases[name]
                return
            else:
                print "Alias `{alias}' already set.".format(alias=name)
                return
        else:
            current_alias = registry._projects[proj_path].get('alias')
            if current_alias:
                prompt =  "Alias `{alias}' already set, overwrite?".format(alias=current_alias)
                answer = option_select(['y','n'], prompt)
                if answer == 'n':
                    print "Aborted."
                    return

def deactivate_virtualenv():
    settings = os.path.join(registry.get_settings_path(), 'source.sh')
    with open(settings, 'w') as file:
        file.write("deactivate\n")

    @classmethod
    def get_subcommands(cls):
        subs = dict()
        for p, meta in registry._projects.items():
            alias = meta.get('alias')
            if alias:
                subs[alias] = PinProjectProxy(p)
            else:
                subs[os.path.basename(p)] = PinProjectProxy(p)
        return subs

def execute(self):
        if not self.root:
            return self.raise_no_project()
        else:
            repeat = True
            while repeat:
                pinpath = os.path.join(self.root, PROJECT_FOLDER)
                print "WARNING: Will destory all data in the .pin directory!"
                os.system("ls %s" % pinpath)
                selection = option_select(['y', 'n'], "Really destroy?")
                if selection == 'n':
                    print "Aborted."
                    return
                elif selection == 'y':
                    shutil.rmtree(pinpath)
                    registry.unregister(self.root)
                    return True
    def done(self):