def get_containers_for_group(inventory, group):
    """Return containers that belong to a particular group.

    Keyword arguments:
    inventory -- inventory dictionary
    group -- group to use to lookup containers

    Will return a list of containers that belong to a group, or None if no
    containers match the group provided.
    """
    if 'hosts' in inventory[group]:
        containers = inventory[group]['hosts']
    else:
        containers = None
    return containers