Passing object expression through one macro to another fails

Created by: johanatan

macro $td {
  case { $($key:expr : $value:expr) (,) ...} => {
    var $key (,) ...
  }
}

macro $td2 {
  case $objBody:expr => {
    $td $objBody
  }
}

$td {a : 5, b : 9, ab : 577, bb : 977}    // semi-works. has misnamed 'a' to '$2'
//$td2 {a : 5, b : 9, ab : 577, bb : 977} // failure to match in 'td'