How do I restrict passed variable to specific values in python?

I am writing the script where I pass values with CLI through argparse module. I am wondering if this is possible to restrict variable to hold pre-defined values, to avoid user mistake. It is not the type restriction, values are consists of letters as well as digits, surely I can write an if block, but I have about 30 pre-defined values, so writing something like

if var is value1 or var is value2 ... or var is value30:
  pass
else:
    print("oops, your value does not fit")

would be painful. What is the proper way of doing this?

With choices:

In [214]: parser = argparse.ArgumentParser()
In [215]: parser.add_argument('--foo', choices=['one','two','three','four']);

Accepted:

In [216]: parser.parse_args('--foo one'.split())
Out[216]: Namespace(foo='one')

rejected:

In [217]: parser.parse_args('--foo five'.split())
usage: ipython3 [-h] [--foo {one,two,three,four}]
ipython3: error: argument --foo: invalid choice: 'five' (choose from 'one', 'two', 'three', 'four')

help:

In [218]: parser.parse_args('-h'.split())
usage: ipython3 [-h] [--foo {one,two,three,four}]

optional arguments:
  -h, --help            show this help message and exit
  --foo {one,two,three,four}

If I'd defined a metavar, the help will be

usage: ipython3 [-h] [--foo CHOICES]

optional arguments:
  -h, --help     show this help message and exit
  --foo CHOICES

Or if the choices is too long, define a type function:

In [222]: def mychoices(astr):
     ...:     if astr in ['one','two','three','four']:
     ...:         return astr
     ...:     else:
     ...:         raise argparse.ArgumentTypeError('Wrong choice')

In [223]: parser = argparse.ArgumentParser()
In [224]: parser.add_argument('--foo', type=mychoices);

In [225]: parser.parse_args('--foo one'.split())
Out[225]: Namespace(foo='one')

In [226]: parser.parse_args('--foo five'.split())
usage: ipython3 [-h] [--foo FOO]
ipython3: error: argument --foo: Wrong choice

In [227]: parser.parse_args('-h'.split())
usage: ipython3 [-h] [--foo FOO]

optional arguments:
  -h, --help  show this help message and exit
  --foo FOO