line.py

#!/usr/bin/env python

# Create a parameter YAML file: parms1.yml that contains
# m: 1
# b: 5


import yaml
import click


def line(x, m=None, b=None):
    return (m * x + b)


@click.command()
@click.argument('filename')
@click.argument('x')
def main(filename, x):
    with open(filename, 'r') as stream:
        try:
            parms = yaml.load(stream)
        except yaml.YAMLError as exc:
            print(exc)
    print(line(int(x), **parms))


if __name__ == '__main__':
    main()