code: function Purry_Error(err_obj){
    function do_purry_error(){
      var o = err_obj.apply(null, arguments);
      o.message = 'Purry:\n\n'+ tt.stack_pos(p(o));
      var err = error(o);
      if (Error.captureStackTrace) Error.captureStackTrace(err, do_purry_error);
      error.discard_callsite(err, /purry_wrapper/);
      return err;
    }
    return do_purry_error;
  }
docs: Private