Oh my, they removed 'cons' :(

    hy 0.11.1 using CPython(default) 3.5.3 on Linux
    => (cons 1 '(2 3))
    (1 2 3)


    hy 0.15.0 using CPython(default) 2.7.13 on Linux
    => (cons 1 '(2 3))
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/hy/importer.py", line 199, in hy_eval
        return eval(ast_compile(expr, "<eval>", "eval"), namespace)
      File "<eval>", line 1, in <module>
    NameError: name 'cons' is not defined