import click
import click_config_file
import yaml


def myprovider(file_path, cmd_name):
    with open(file_path) as config_file:
        return yaml.safe_load(config_file)

@click.command()
@click.option("--opt", default="from-default")
@click_config_file.configuration_option(
    provider=myprovider, config_file_name="config.yaml", implicit=False
)
def main(opt):
    print("opt", opt)


if __name__ == "__main__":
    main(auto_envvar_prefix="FOO")