为什么我的Hy版本未知且deftag未定义？

Question

为什么要hy unknown？

如何使用deftag？

来自http://docs.hylang.org/en/stable/language/api.html#deftag的片段

    gt@gt-ThinkPad-X230:~$ hy --spy
    hy unknown using CPython(default) 3.6.8 on Linux
    => (deftag ♣ [expr] `[~expr ~expr])
    from hy import HyList
    deftag(♣, [expr], HyList((([] + [expr]) + [expr])))
    Traceback (most recent call last):
      File "/usr/lib/python3.6/code.py", line 91, in runcode
        exec(code, self.locals)
      File "<input>", line 1, in <module>
    NameError: name 'deftag' is not defined
    => (exit)
exit()