def ext (func_name, key='', value='', opts={})

      k = key.to_s
      v = value.to_s

      outlen_op(
        :tcrdbext,
        func_name.to_s,
        compute_ext_opts(opts),
        k, Rufus::Tokyo.blen(k),
        v, Rufus::Tokyo.blen(v))
    end
def ext (func_name, key='', value='', opts={})

      k = key.to_s
      v = value.to_s

      outlen_op(
        :tcrdbext,
        func_name.to_s,
        compute_ext_opts(opts),
        k, Rufus::Tokyo.blen(k),
        v, Rufus::Tokyo.blen(v))
    end
Calls a lua embedded function
 (http://tokyocabinet.sourceforge.net/tyrantdoc/#luaext)

 Options are :global_locking and :record_locking

 Returns the return value of the called function.

 Nil is returned in case of failure.