lodash/_isFlattenable.js

define(['./_Symbol', './isArguments', './isArray'], function(Symbol, isArguments, isArray) {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /** Built-in value references. */
  var spreadableSymbol = Symbol ? Symbol.isConcatSpreadable : undefined;

  /**
   * Checks if `value` is a flattenable `arguments` object or array.
   *
   * @private
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is flattenable, else `false`.
   */
  function isFlattenable(value) {
    return isArray(value) || isArguments(value) ||
      !!(spreadableSymbol && value && value[spreadableSymbol]);
  }

  return isFlattenable;
});