code: function defaultCharset (charset) {
      // set charset
      if (defined(charset)) {
          getGlobal().defaultCharset = charset
          // return class when setting
          return ImmutableCoreModel
      }
      // return engine
      return getGlobal().defaultCharset
  }
docs: @function defaultCharset
  
  get/set global default charset used when creating tables
  
  @param {string|undefined} charset
  
  @returns {ImmutableCoreModel|string}