Method check_initialized

python/src/array.cpp:36–41

    return *this;
  }
  void check_initialized() {
    if (!initialized_) {
      throw std::invalid_argument(
          "Must give indices to array.at (e.g. `x.at[0].add(4)`).");
    }
  }

  mx::array add(const ScalarOrArray& v) {
    check_initialized();