def _extract_array(array, shape, position):
    """Helper function to extract parts of a larger array.

    Simple implementation of an array extract function , because
    `~astropy.ndata.utils.extract_array` introduces too much overhead.`

    Parameters
    ----------
    array : `~numpy.ndarray`
        The array from which to extract.
    shape : tuple or int
        The shape of the extracted array.
    position : tuple of numbers or number
        The position of the small array's center with respect to the
        large array.
    """
    x_width = shape[1] // 2
    y_width = shape[0] // 2
    y_lo = position[0] - y_width
    y_hi = position[0] + y_width + 1
    x_lo = position[1] - x_width
    x_hi = position[1] + x_width + 1
    return array[y_lo:y_hi, x_lo:x_hi]