def return_agar_plates(wells=6):
    """Returns a dict of all available agar plates.

    Parameters
    ----------
    wells : integer
        Integer of the number of wells in the plate, 1 or 6.
        Default: 6 for 6-well plate

    Returns
    -------
    dict
        plates with plate identity as key and kit_id as value

    Raises
    ------
    ValueError
        If wells is not a integer equal to 1 or 6

    """
    if wells == 6:
        plates = {'lb_miller_50ug_ml_kan': 'ki17rs7j799zc2',
            'lb_miller_100ug_ml_amp': 'ki17sbb845ssx9',
            'lb_miller_100ug_ml_specto': 'ki17sbb9r7jf98',
            'lb_miller_100ug_ml_cm': 'ki17urn3gg8tmj', 'lb_miller_noAB':
            'ki17reefwqq3sq'}
    elif wells == 1:
        plates = {'lb_miller_50ug_ml_kan': 'ki17t8j7kkzc4g',
            'lb_miller_100ug_ml_amp': 'ki17t8jcebshtr',
            'lb_miller_100ug_ml_specto': 'ki17t8jaa96pw3',
            'lb_miller_100ug_ml_cm': 'ki17urn592xejq', 'lb_miller_noAB':
            'ki17t8jejbea4z'}
    else:
        raise ValueError('Wells has to be an integer, either 1 or 6')
    return plates
