Lists the available/mounted/unmounted sftp systems.
        Usage: sftpman ls {what}
        Where {what} is one of: available, mounted, unmounted

def command_ls(self, list_what):
        """Lists the available/mounted/unmounted sftp systems.
        Usage: sftpman ls {what}
        Where {what} is one of: available, mounted, unmounted
        """
        if list_what in ('available', 'mounted', 'unmounted'):
            callback = getattr(self.environment, 'get_%s_ids' % list_what)
            lst = callback()
        else:
            lst = []
        if len(lst) != 0:
            print(("\n".join(lst)))