Как проанализировать аргументы на обещание в JavaScript

const some_function = (username, password) =>
{
 return new Promise((resolve, reject) =>
 {
  /*stuff using username, password*/

  if ( /* everything turned out fine */ )
  {
   resolve("Stuff worked!");
  }
  else
  {
   reject(Error("It broke"));
  }
 });
};

some_module.some_function(username, password).then(uid =>
{
 // stuff
});
REX OMIV