Process local commands

def _list(self, args):
        '''
        Process local commands
        '''
        args.pop(0)
        command = args[0]
        if command == 'packages':
            self._list_packages(args)
        elif command == 'files':
            self._list_files(args)
        elif command == 'repos':
            self._repo_list(args)
        else:
            raise SPMInvocationError('Invalid list command \'{0}\''.format(command))