yaml_overrides.py

import collections
import yaml

# Try to preserve order in the front matter.

def dict_representer(dumper, data):
    return dumper.represent_dict(data.items())

def dict_constructor(loader, node):
    return collections.OrderedDict(loader.construct_pairs(node))

_mapping_tag = yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG
yaml.Dumper.add_representer(collections.OrderedDict, dict_representer)
yaml.Loader.add_constructor(_mapping_tag, dict_constructor)
yaml.FullLoader.add_constructor(_mapping_tag, dict_constructor)

# Represent null as blank.

def none_representer(dumper, _):
    return dumper.represent_scalar('tag:yaml.org,2002:null', '')

yaml.Dumper.add_representer(type(None), none_representer)