I have a dataset which is made up of nested sequences, so for example one data point looks like this: 

```
p1 = [[1,1,1], [2,2], [3,3,3]]

```

but another data point could look like this:

```
p2 = [[1,1], [2,2,2,2,2]]

```

I am not sure how I can save lists of lists in TFRecords as all the examples I found only save **non-nested** lists of varying length. I plan to then uses padded\_batch to create 3D tensors of the shape 
`[batch size, max number of lists, max number of tokens in a list]`