docs: function props(dest, pds, src, isrc, ndflt, nm, nmsrc) {
      var asrt = nm && src;
      if (asrt) assert.ok(dest, 'no ' + nm);
      var i = pds.length;
      while (i--) {
          if (asrt) prop(dest, pds[i], src, isrc, ndflt, nm, nmsrc);
          else prop(dest, pds[i], src, isrc, ndflt);
      }
      return dest;
  }