code: function elt(eltType, numargs) {
  	return function () {
  		var args = Array.prototype.slice.call(arguments);
  		var len = args.length;
  		if (len !== numargs)
  			throw eltType + ' expects ' + numargs	+ ' arguments, but given ' + len;
  		return {'t':eltType,'c':(len === 1 ? args[0] : args)};
  	};
  }
docs: Utility for creating constructor functions