the mechanism for registering converters didn't work for me

[MarcoCostantini]

I tried the example at the bottom of page https://github.com/OpenMath/py-openmath: I tried to copy and paste each line, but it didn't work for me:

Finally, this class contains a mechanism for registering converters.
$ python3
Python 3.8.2 (default, Mar 13 2020, 10:14:16)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from fractions import Fraction
>>> from openmath import openmath as om
>>> from openmath.convert import DefaultConverter as converter
>>> def to_om_rat(obj):
...     return om.OMApplication(om.OMSymbol('rational', cd='nums1'),
...             list(map(converter.to_openmath, [obj.numerator, obj.denominator])))
...
>>> def to_py_rat(obj):
...     return Fraction(converter.to_python(obj.arguments[0]), converter.to_python(obj.arguments[1]))
...
>>> converter.register(Fraction, to_om_rat, 'nums1', 'rational', to_py_rat)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'BasicPythonConverter' object has no attribute 'register'
>>>

[defeo]

Thanks for filing these issues! I have literally zero bandwidth for this, at the moment, but if you'd like to submit a pull request, I'd be happy to review it.