In the Writing custom array containers guide, the signature for __array__ is given as

def __array__(self):

which does not include the optional dtype argument. If a container class implementer follows the signature in the guide (like I did in hgrecco/pint#953), it breaks functionality with libraries (such as matplotlib) that rely on being able to use the dtype argument.

Would it be reasonable to update the custom containers guide to include this optional argument, with an added example block to illustrate its use? If so, I can submit a PR.

xref hgrecco/pint#974, hgrecco/pint#975