From within a predefined set of cidrs print a subnet from a requested section

subnet-get.py

import sys

import netaddr


# These are the predefined subnets which will print a given section. There
# are a total of 64 sections in either network.
# The constant is a list of tuples.
LAB_CIDRS = [
    ('tunnel', '172.29.236.0/22', 28),
    ('container', '10.240.0.0/16', 22)
]


def _get_cidr(index_num, cidr, section):
    """Return a subnet from within a CIDR.

    :param index_num: ``int``
    :param cidr: ``str``
    :param section: ``int``
    :returns: ``str``
    """

    _cidr = netaddr.IPNetwork(cidr)
    return [i for i in _cidr.subnet(section)][index_num]


def main(index_num):
    """Print the type and lab cidr from a user defined index.

    :param index_num: ``int``
    """
    if index_num > 63:
        raise SystemExit(
            'Number must be between 0 - 64.'
        )

    for name, cidr, section, in LAB_CIDRS:
        print(
            'Type: [ %s ] Subnet: [ %s ]' % (
                name, _get_cidr(
                    index_num=index_num,
                    cidr=cidr,
                    section=section
                )
            )
        )


if __name__ == "__main__":
    main(index_num=int(sys.argv[1]))