etl.py

def testing(foo, fname, **kwargs):
    print(foo, fname, kwargs)

def parse_args(a):
    r, extra = [], []
    for i in a:
        if "--" in i and not "=" in i:
            print("error")
        if "--" in i:
            r.append(re.split("=", i[2:], 2))
        else:
            extra.append(i)
    return dict(r + [['__extra', extra]])

cmds = { "testing": testing }

if __name__ == "__main__":
    cmds[sys.argv[1]](**parse_args(*sys.argv[2:]))