function iteratee(func) {
      return baseIteratee(typeof func == 'function' ? func : baseClone(func, CLONE_DEEP_FLAG));
    }
Creates a function that invokes `func` with the arguments of the created
function. If `func` is a property name, the created function returns the
property value for a given element. If `func` is an array or object, the
created function returns `true` for elements that contain the equivalent
source properties, otherwise it returns `false`.

@static
@since 4.0.0
@memberOf _
@category Util
@param {*} [func=_.identity] The value to convert to a callback.
@returns {Function} Returns the callback.
@example

var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']