code: function freezeData (freezeData) {
      if (defined(freezeData)) {
          // set default
          immutable.defaultFreezeData = freezeData ? true : false
          // return immutable
          return ImmutableCore
      }
      // return default value
      return immutable.defaultFreezeData
  }
docs: @function freezeData
  
  get/set the default freezeData option
  
  @param {boolean} freezeData
  
  @returns {ImmutableCore|boolean}