Change conditions using loop and array in python

i have and old script in python, where in

if __name__ == '__main__': <br>

We call arguments of functions. And if it argument equals some string we should call function. Old code.

if sys.argv[1] == 'add':
    sys.exit(add(db, usr))
if sys.argv[1] == 'rem':
    sys.exit(rem(db, usr))
if sys.argv[1] == 'rmusr':
    sys.exit(rmusr(db, usr))

At the first time, i thought about "switch case", but how i find out, python does not have it. And i tried to loop and array. Can i use it on this ? Sorry, i started to lear python, 2 hours ago. But it is very interesting, and i hope, that you can help me.

 actions = ['add','rem','rmusr']
    for a in actions:
    if sys.argv[1] == 'a':
        sys.exit(a(db, usr))

Is it correct ? How i find out, we should not call variables with "$". Please help.