var aCallable = require('../internals/a-callable');
var anObject = require('../internals/an-object');
var getIteratorMethod = require('../internals/get-iterator-method');

module.exports = function (argument, usingIterator) {
  var iteratorMethod = arguments.length < 2 ? getIteratorMethod(argument) : usingIterator;
  if (aCallable(iteratorMethod)) return anObject(iteratorMethod.call(argument));
  throw TypeError(String(argument) + ' is not iterable');
};