var coreJsData = require('./_coreJsData');
  
  /** Used to detect methods masquerading as native. */
  var maskSrcKey = (function() {
    var uid = /[^.]+$/.exec(coreJsData && coreJsData.keys && coreJsData.keys.IE_PROTO || '');
    return uid ? ('Symbol(src)_1.' + uid) : '';
  }());
  
  /**
   * Checks if `func` has its source masked.
   *
   * @private
   * @param {Function} func The function to check.
   * @returns {boolean} Returns `true` if `func` is masked, else `false`.
   */
  function isMasked(func) {
    return !!maskSrcKey && (maskSrcKey in func);
  }
  
  module.exports = isMasked;