How can one split a column like `df.value` 

```
value
--------
Top/Animals/Cat
Top/Dog
Pig/Guineea/Piglet

```

into multiple columns 

```
val1 |   val2   | val3 |
Top    Animals     Cat
NaN      Top       Dog
Pig    Guineea    Piglet

```

such that I have the number of columns of the longest string and NaN where other strings are not the same length?