huzzah.py

def visit(node, parent, field_name, field_index):
    node_item = handle_item(node, parent, field_name, field_index)
    if node_item is None:
        return

    fields = {}
    for field_name, field in ast.iter_fields(node):
        fieldset = fields.setdefault(field_name, [])
        if isinstance(field, list):
            for i, item in enumerate(field):
                ret = yield from visit(item, node, field_name, i)
                fieldset.append(ret)
        else:
            ret = yield from visit(field, node, field_name, None)
            fieldset.append(ret)

    node_item['fields'] = fields
    yield node_item
    return node_item