How to use the shyaml.ShyamlSafeDumper.add_representer function in shyaml

try:
    ## included in standard lib from Python 2.7
    from collections import OrderedDict
except ImportError:  ## pragma: no cover
    ## try importing the backported drop-in replacement
    ## it's available on PyPI
    from ordereddict import OrderedDict


## Ensure that there are no collision with legacy OrderedDict
## that could be used for omap for instance.
class MyOrderedDict(OrderedDict):
    pass


ShyamlSafeDumper.add_representer(
    MyOrderedDict,
    lambda cls, data: cls.represent_dict(data.items()))


def construct_omap(cls, node):
    ## Force unfolding reference and merges
    ## otherwise it would fail on 'merge'
    cls.flatten_mapping(node)
    return MyOrderedDict(cls.construct_pairs(node))


ShyamlSafeLoader.add_constructor(
    yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG,
    construct_omap)