--- /dev/null
+var global = require('../internals/global');
+var isCallable = require('../internals/is-callable');
+var tryToString = require('../internals/try-to-string');
+
+var TypeError = global.TypeError;
+
+// `Assert: IsCallable(argument) is true`
+module.exports = function (argument) {
+ if (isCallable(argument)) return argument;
+ throw TypeError(tryToString(argument) + ' is not a function');
+};