docs: function _addMethod(methodDictionary, func, name) {
    expect(func).to.be.a(
      'function',
      'Invalid argument "func" when adding a method called "' + name + '" in a ' +
      'MethodDictionary (it has to be a function)'
    );
  
    Object.defineProperty(methodDictionary, name, {
      value: func,
      enumerable: true,
      writable: false,
      configurable: false
    });
  }