python3 -m pip install sphinxcontrib-chapeldomain

git clone https://github.com/chapel-lang/sphinxcontrib-chapeldomain
cd sphinxcontrib-chapeldomain
python setup.py install

.. chpl:module:: GMP
    :synopsis: multiple precision integer library

.. chpl:record:: BigNum

    multiple precision instances

    .. chpl:method:: proc add(a:BigNum, b:BigNum)

        Add two big ints, ``a`` and ``b``, and store the result in ``this``
        instance.

        :arg a: BigNum to be added
        :type a: BigNum

        :arg BigNum b: BigNum to be added

        :returns: nothing, result is stored in current instance

    .. chpl:itermethod:: iter these() ref

        Arbitrary iterator that returns individual digits of this instance.

        :ytype: reference
        :yields: reference to each individual digit of BigNum