Literal block scalars with PyYAML's dump

literal_string.py

import yaml
from yaml.representer import SafeRepresenter

class LiteralString(str):
    pass


def change_style(style, representer):
    def new_representer(dumper, data):
        scalar = representer(dumper, data)
        scalar.style = style
        return scalar
    return new_representer


represent_literal_str = change_style('|', SafeRepresenter.represent_str)


yaml.add_representer(LiteralString, represent_literal_str)

markdown = """
# Markdown Document

Foo Bar Baz
"""

data = {'string': LiteralString(markdown)}

print(yaml.safe_dump(data))