Range-based for loop to iterate over a NumPy array?

[CsatiZoltan]

I have an array arr of type pybind11::detail::unchecked_reference<int, 1> over which I want to iterate.
The standard for loop works:

const size_t n_elem = arr.shape (0);
for (size_t i = 0; i < n_elem; ++i) {
    int elem = arr(i);
    // do something with it
}

My code would be more expressive with a range-based for loop:

for (const auto &elem : arr) {
    // do something with it
}

but it does not compile:

error: ‘begin’ was not declared in this scope

Even the static analyzer warns me:

this range-based 'for' statement requires a suitable "begin" function and none was found

How could I iterate over a NumPy array elegantly?