Export datasources to YAML

def export_datasources(print_stdout, datasource_file,
                       back_references, include_defaults):
    """Export datasources to YAML"""
    data = dict_import_export.export_to_dict(
        session=db.session,
        recursive=True,
        back_references=back_references,
        include_defaults=include_defaults)
    if print_stdout or not datasource_file:
        yaml.safe_dump(data, stdout, default_flow_style=False)
    if datasource_file:
        logging.info('Exporting datasources to %s', datasource_file)
        with open(datasource_file, 'w') as data_stream:
            yaml.safe_dump(data, data_stream, default_flow_style=False)