function isFunction(value) {
      // Use `|| false` to avoid a Chakra bug in compatibility modes of IE 11.
      // See https://github.com/jashkenas/underscore/issues/1621.
      return typeof value == 'function' || false;
    }
Checks if `value` is classified as a `Function` object.

@static
@memberOf _
@category Lang
@param {*} value The value to check.
@returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
@example

_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false