Can I use TOML variables to nest TOML tables in other TOML tables?

Can I put a TOML table into a TOML variable and then use that variable in another TOML table? I would like to replicate JSON ouput like this:

group1 = {
    "key1": "value1"
    "key2": "value2"
    "key3": {
        "key1": "value4"
        "key2": "value5"
        "key3": "value6"
    }
}

group2 = {
    "key1": "value1"
    "key2": "value2"
    "key3": {
        "key1": "value4"
        "key2": "value5"
        "key3": "value6"
    }
}

mainGroup = {
    "key1": "value1"
    "key2": "value2"
    "key3": group1
    "key4": {
        "key1": "value3"
        "key2": "value3"
        "key3": group2
    }
    "key5": {
        "key1": group1
        "key2": group2
    }
}