def getContainer(name_or_id):
    '''Get the container with the given name or ID (str). No side effects.
    Idempotent. Returns None if the container does not exist. Otherwise, the
    continer is returned'''
    require_str("name_or_id", name_or_id)

    container = None
    try:
        container = client.containers.get(name_or_id)
    except NotFound as exc:
        # Return None when the container is not found
        pass
    except APIError as exc:
        eprint("Unhandled error")
        raise exc

    return container
Get the container with the given name or ID (str). No side effects.
    Idempotent. Returns None if the container does not exist. Otherwise, the
    continer is returned