[
    {
        "finite_prob": 0.8,
        "interval_prob": 0.1,
        "special_prob": 0.1,
        "max_size": 6,
        "element_type": "letter"
    },
    {
        "finite_prob": 0.6,
        "interval_prob": 0.3,
        "special_prob": 0.1,
        "max_size": 4,
        "element_type": "number"
    },
    {
        "finite_prob": 0.9,
        "interval_prob": 0.05,
        "special_prob": 0.05,
        "max_size": 3,
        "element_type": "number"
    },
    {
        "finite_prob": 0.7,
        "interval_prob": 0.2,
        "special_prob": 0.1,
        "max_size": 5,
        "element_type": "mixed"
    }
]