Suggestion of change to POV

I would like to suggest a minor change to Tree because I feel trees are rendered better using pprint instead of json:

import io
from pprint import pprint

    def __str__(self, indent=None):
        with io.StringIO() as F:
            pprint(self.__dict__(), width = 1, stream = F)
            return F.getvalue()
    def __repr__(self):
        return str(self)

You should give this a read!