PyonObject.dump fails for xml when path has numbers

[dapryor]

import pyon
p = pyon.PyonObject("/test/123")
p.dump(output_format='xml')

AttributeError: 'int' object has no attribute 'isdigit'```

[lagmoellertim]

Hey, I'm currently looking to change the xml conversion library, since it has many other bugs that makes it pretty much unusable for many cases. If you know a library which also includes custom attributes, feel free to recommend one.

[dapryor]

looks like neither the json module nor the dicttoxml module support intergers as keynames:

Example:

json.loads('{"hey": {123: "hey"}}')

json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 10 (char 9)

Found this issue on the dicttoxml page: quandyfactory/dicttoxml#61

Maybe it would be better to mimic the way these two modules work and convert integers to strings before adding them as keys?