1  // Run-time checking of preconditions.
 2  
 3  function fail(message) {
 4      throw new Error(message);
 5  }
 6  
 7  // Precondition function that checks if the given predicate is true.
 8  // If not, it will throw an error.
 9  function argument(predicate, message) {
10      if (!predicate) {
11          fail(message);
12      }
13  }
14  
15  export { fail, argument, argument as assert };
16  export default { fail, argument, assert: argument };